Proposed 2025 Revision of the International Code of Nomenclature of Prokaryotes

1 Yellow highlighting: changes proposed by the ICNP editorial board prior to the start of the discussion on Slack. Turquoise highlighting – changes proposed in the course of the Slack discussion (see attached document annotated with all comments raised). 2022 Revision , emended with later changes already approved by the ICSP 2025 Revision General Consideration 1 The progress of prokaryotic microbiology is advanced by a precise and standardized system of nomenclature accepted by the international community of microbiologists. General Consideration 1 The progress of prokaryotic microbiology is advanced by a precise and standardized system of nomenclature accepted by the international community of microbiologists. General Consideration 2 Scientific names must be regulated by internationally accepted Rules, to achieve and maintain order in nomenclature. General Consideration 2 Scientific names must be regulated by internationally accepted Rules, to achieve and maintain order in nomenclature General Consideration 3 The Rules that govern the nomenclature used in the biological sciences are embodied in International Codes of Nomenclature (see Appendix 1 for a list of these Codes). General Consideration 3 The Rules that govern the nomenclature used in the biological sciences are embodied in International Codes of Nomenclature (see Appendix 1 for a list of these Codes). General Consideration 4 Rules of nomenclature do not govern the delimitation of taxa nor determine their relations. The Rules prescribe the procedures for creating and proposing new names and for assessing the correctness of the names applied to defined taxa. General Consideration 4 Rules of nomenclature do not govern the delimitation of taxa nor determine their relations. The Rules prescribe the procedures for creating and proposing new names and for assessing the correctness of the names applied to defined taxa. 2 General Consideration 5 This Code of Nomenclature of Prokaryotes applies to all Prokaryotes. The nomenclature of eukaryotic microbial groups is provided for by other Codes: fungi and algae by the International Code of Nomenclature for algae, fungi and plants; protozoa by the International Code of Zoological Nomenclature. The nomenclature of viruses is provided for by the International Code of Virus Classification and Nomenclature (see Appendix 1). Note. “Prokaryotes” covers those organisms that are variously recognized as, e.g., Archaea, Archaebacteria, Archaeobacteria, Bacteria, Cyanobacteria, Cyanophyceae, Eubacteria, Schizomycetes, and Schizophycetes. If a taxon originally assigned to the Cyanophyceae/Cyanobacteria was named under the provisions of the International Code of Nomenclature for algae, fungi, and plants, any of its names need satisfy only the requirements of that Code for status equivalent to valid publication under the International Code of Nomenclature of Prokaryotes. . General Consideration 5 This International Code of Nomenclature of Prokaryotes applies to all Prokaryotes. The nomenclature of eukaryotic microbial groups is provided for by other Codes: fungi and algae by the International Code of Nomenclature for algae, fungi, and plants; protozoa by the International Code of Zoological Nomenclature. The nomenclature of viruses is provided for by the International Code of Virus Classification and Nomenclature (see Appendix 1) Note. “Prokaryotes” covers those organisms that are variously recognized as e.g., Archaea, Archaebacteria, Archaeobacteria, Bacteria, Cyanobacteria, Cyanophyceae, Eubacteria, Schizomycetes, and Schizophycetes. If a taxon originally assigned to the Cyanophyceae/Cyanobacteria was named under the provisions of the International Code of Nomenclature for algae, fungi, and plants, any of its names need satisfy only the requirements of that Code for status equivalent to valid publication under the International Code of Nomenclature of Prokaryotes, unless otherwise expressly stated in the Rules. General Consideration 6 This Code is divided into Principles, Rules and Recommendations. (1) The Principles (Chapter 2) form the basis of the Code, and the Rules and Recommendations are derived from them. General Consideration 6 This Code is divided into Principles, Rules, and Recommendations, and Appendices. 3 (2) The Rules (Chapter 3) are designed to make the Principles effective, to reassess the nomenclature of the past and to provide for the nomenclature of the future. (3) The Recommendations (Chapter 3) deal with subsidiary points and are appended to the Rules which they supplement. Recommendations do not have the force of Rules; they are intended to be guides to desirable practice in the future. Names contrary to a Recommendation cannot be rejected for this reason. (4) Provisions for emendations of Rules, for special exceptions to Rules, and for interpretation of the Rules have been made by the establishment of the International Committee on Systematics of Prokaryotes (ICSP) and the ICSP Judicial Commission, which acts on behalf of the ICSP (see Rule 1b and Statutes of the International Committee on Systematics of Prokaryotes). Opinions issued by the Judicial Commission become effective after receipt of seven or more affirmative votes from Commissioners, but may be rescinded by the ICSP, as provided for in the ICSP Statutes. The official journal of the ICSP is the International Journal of Systematic and Evolutionary Microbiology (IJSEM), formerly International Journal of Systematic Bacteriology (IJSB), formerly the International Bulletin of Bacteriological Nomenclature and Taxonomy (IBBNT). (Some other journal could be specified by the ICSP if required. Such possible future specification is implicit in the use of “International Journal of Systematic and Evolutionary Microbiology” or “IJSEM” throughout this Code, but is not always repeated at each mention.) (5) Appendices are added to assist in the application of this Code (see Table of Contents). (1) The Principles ( Chapter 2) form the basis of the Code , and the Rules and Recommendations are derived from them. (2) The Rules (Chapter 3) are designed to make the Principles effective, to reassess the nomenclature of the past and to provide for the nomenclature of the future. (3) The Recommendations (Chapter 3) deal with subsidiary points and are appended to the Rules that they supplement. Recommendations do not have the force of Rules; they are intended to be guides to desirable practice in the future. Names contrary to a Recommendation cannot be replaced or rejected for this reason. (4) Provisions for emendations of Rules this Code, for special exceptions to Rules, and for interpretation of the Rules this Code have been made by the establishment of the International Committee on Systematics of Prokaryotes (ICSP) and its Judicial Commission, which acts on behalf of the ICSP (see Rule 1b and Statutes of the International Committee on the Systematics of Prokaryotes). Opinions issued by the Judicial Commission become effective as provided for in the ICSP Statutes. The official journal of the ICSP is the International Journal of Systematic and Evolutionary Microbiology (IJSEM), formerly International Journal of Systematic Bacteriology (IJSB), formerly the International Bulletin of Bacteriological Nomenclature and Taxonomy (IBBNT). (Some other journal could be specified by the ICSP if required. Such possible future specification is implicit in the use of “International Journal of Systematic and Evolutionary Microbiology” or “IJSEM” throughout this Code, but is not always repeated at each mention.) 4 (6) Definitions of certain words used in the Code are provided. Such words are indicated in boldface type in the clause concerned, and they may be printed in boldface type elsewhere in this Code. (7) The Notes added to General Considerations, Principles, Rules and Recommendations are intended to clarify the preceding text and are an integral part of the corresponding text (5) Appendices are added to assist in the application of this Code (see Table of Contents). (6) Definitions of certain words used in the Code are provided. Such words are indicated in boldface type in the clause concerned, and they may be printed in boldface type elsewhere in this Code. (7) The Notes added to General Considerations, Principles, Rules, and Recommendations, and Appendices are intended to clarify the preceding text and are an integral part of the corresponding text. General Consideration 7 Nomenclature deals with the following: (1) Terms used to denote the taxonomic categories, e.g., “species”, “family” and “phylum”. (2) Relative ranks of the categories (see Rule 5). (3) Names applied to individual taxa. A taxonomic group is referred to throughout this Code as a taxon; plural, taxa. ‘Taxonomic group’ is used in this Code to refer to any group of organisms treated as a named group in a taxonomy; it may or may not correspond to a category. Examples: Name of a species, Pseudomonas (generic name) aeruginosa (specific epithet); name of a genus, Pseudomonas; name of a family, Pseudomonadaceae; name of an order, Pseudomonadales. General Consideration 7 Nomenclature deals with the following: (1) Terms used to denote the taxonomic categories, e.g., “species”, “family” and “phylum”. (2) Relative ranks of the categories (see Rules 5a and 5b). (3) Names applied to individual taxa. A taxonomic group is referred to throughout this Code as a taxon, plural taxa. “Taxonomic group” is used in this Code to refer to any group of organisms treated as a named group in a taxonomy; it may or may not correspond to a category. Examples: Name of a species, Pseudomonas (generic name) aeruginosa (specific epithet); name of a genus, Pseudomonas; name of a family, Pseudomonadaceae; name of an order, Pseudomonadales. 5 General Consideration 8 The International Code of Nomenclature of Prokaryotes is an instrument of scientific communication. Names have meaning only in the context in which they were formed and used. General Consideration 8 The International Code of Nomenclature of Prokaryotes is an instrument of scientific communication. Names have meaning only in the context in which they were formed and used. CHAPTER 2. PRINCIPLES Principle 1 The essential points in nomenclature are to: (1) Aim at stability of names; (2) Avoid or reject the names that cause error or confusion; (3) Avoid the useless creation of names; (4) Nothing in this Code may restrict the freedom of taxonomic thought or action. Note. ‘Name’ in this Code, unless otherwise indicated, is used to refer to names applied to prokaryotes that have been validly published, whether legitimate or illegitimate (see Chapter 3, Section 3). . CHAPTER 2. PRINCIPLES Principle 1 The essential points in nomenclature are to: (1) Aim at stability of names. (2) Avoid or reject the names that cause error or confusion. (3) Avoid the useless creation of names. (4) Nothing in this Code may restrict the freedom of taxonomic thought or action. Note. “Name” in this Code, unless otherwise indicated, is used to refer to names applied to prokaryotes that have been validly published, whether legitimate or illegitimate (see Chapter 3, Section 3). Principle 2 The nomenclature of prokaryotes is not independent of botanical and zoological nomenclature. When naming new taxa in the rank of genus or higher, due consideration is to be given to avoiding names which are Principle 2 The nomenclature of prokaryotes is not independent of botanical and zoological nomenclature. When naming new taxa in the rank of genus or higher, due consideration is to be given to avoiding names that are 6 regulated by the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi and plants. Note. This principle takes effect with publication of acceptance of this change by the ICSP (from 1 January 2001) and is not retroactive. For information about lists of names of zoological and botanical taxa, see Appendix 3. regulated by the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants. Note. This principle takes took effect with publication of acceptance of this change by the ICSP (from on 1 January 2001) and is not retroactive. For information about lists of names of zoological and botanical taxa, see Appendix 3. Principle 3 The names of all taxa are Latin or latinized words treated as Latin, regardless of their origin. They are usually taken from Latin or Greek (see Chapter 3, Section 9, and Appendix 9). Principle 3 The names of all taxa are Latin or Latinized words treated as Latin, regardless of their origin. They are usually taken from Latin or Greek (see Chapter 3, Section 9, and Appendix 9). Principle 4 The purpose of giving a name to a taxon is to supply a means of referring to it rather than to indicate the characters or the history of the taxon. Principle 4 The purpose of giving a name to a taxon is to supply a means of referring to it rather than to indicate the characters or the history of the taxon. Principle 5 The application of the names of taxa is determined by means of nomenclatural types, referred to in this Code as types (see Chapter 3, Section 4). Principle 5 The application of the names of taxa is determined by means of nomenclatural types, referred to in this Code as types (see Chapter 3, Section 4). Principle 6 The correct name of a taxon is based upon valid publication, legitimacy and priority of publication (see Chapter 3, Section 5). Pr inciple 6 The correct name of a taxon is based upon valid publication, legitimacy and priority of publication (see Chapter 3, Section 5). 7 Principle 7 A name of a taxon has no status under the Rules and no claim to recognition unless it is validly published (see Chapter 3, Section 5). Principle 7 A name of a taxon has no status under the Rules and no claim to recognition unless it is validly published (see Chapter 3, Section 5; for prostatus, see Section 10). Principle 8 Each phylum or taxon of a lower rank with a given circumscription, position, and rank can bear only one correct name, i.e., the earliest that is in accordance with the Rules of this Code. Provision has been made for exceptions to this Principle (see Rules 23a and 23b). Note 1. The name of a species is a binary combination of generic name and specific epithet. Note 2. (i) Circumscription of the taxon is an indication of its limits; (ii) position of a taxon is an indication in which higher taxon it is placed (see also Rule 23a); and (iii) rank of the taxon is its level in the hierarchical sequence of taxonomic categories. Principle 8 Each taxon with a given circumscription, position, and rank can bear only one correct name, i.e., the earliest that is in accordance with the Rules of this Code. Provision has been made for exceptions to this Principle (see Rules 23a and 23b). Note 1. The name of a species is a binary combination of generic name and specific epithet. Note 2. (i) Circumscription of the taxon is an indication of its limits; (ii) position of a taxon is an indication in which higher taxon it is placed (see also Rule 23a); and (iii) rank of the taxon is its level in the hierarchical sequence of taxonomic categories. Principle 9 The name of a taxon should not be changed without sufficient reason; if necessary, changes should be based upon further taxonomic studies or on the necessity of expunging a name that is contrary to the Rules of this Code Principle 9 The name of a taxon must not be changed without sufficient reason; if necessary, changes must be based upon further taxonomic studies or on the necessity of expunging rejecting or replacing a name that is contrary to the Rules a Rule of this Code. CHAPTER 3. RULES OF NOMENCLATURE WITH RECOMMENDATIONS CHAPTER 3. RULES OF NOMENCLATURE WITH RECOMMENDATIONS 8 Section 1. General Rule 1a This revision of the International Code of Nomenclature of Prokaryotes supersedes all previous revisions of the Bacteriological Code and the International Code of Nomenclature of Prokaryotes (see Appendix 1). It shall be cited as the Prokaryotic Code (2022 Revision) and will apply from the date of publication online. Section 1. General Rule 1a This revision of the International Code of Nomenclature of Prokaryotes supersedes all previous revisions of the International Code of Nomenclature of Bacteria and the International Code of Nomenclature of Prokaryotes (see Appendix 1). It shall be cited as the Prokaryotic Code (2025 Revision) and will apply from the date of publication online. Rule 1b Alterations to this Code can be made only by the ICSP. Proposals for modifications should be made as specified in the Statutes of the ICSP. Rule 1b Alterations to this Code can be made only by the ICSP. Proposals for modifications, if any, must be made as specified in the Statutes of the ICSP. Rule 2 The Rules of this Code are retroactive, except where specified. Examples: Rule 18a, Rule 30. Rule 2 The Rules of this Code are retroactive, except where specified. Examples: Rule 18a, Rule 30. Rule 3 Names contrary to a Rule cannot be maintained, except that the ICSP, on the recommendation of the Judicial Commission, may make exceptions to the Rules (see Rule 23a). Rule 3 Names contrary to a Rule cannot be maintained, except that the Judicial Commission may make exceptions to the Rules (see Rule 23a and Appendix 4). Rule 4 Rule 4 9 In the absence of a relevant Rule or where the consequences of a Rule are uncertain, a summary in which all pertinent facts are outlined should be submitted to the Judicial Commission for consideration (see Appendix 8 for preparation of a Request for an Opinion). In the absence of a relevant Rule or where the consequences of a Rule are uncertain, a summary in which all pertinent facts are outlined should be submitted to the Judicial Commission for consideration (see Appendix 8 for preparation of a Request for an Opinion). Section 2. Ranks of Taxa Rule 5a Definitions of the taxonomic categories may vary with individual opinion, but the relative order of these categories may not be altered in any classification. Section 2. Ranks of Taxa Rule 5a Definitions of the taxonomic categories may vary with individual opinion, but the relative order of these categories may not be altered in any classification. Rule 5b The taxonomic categories above and including subspecies, which are covered by these Rules, are given below in ascending taxonomic rank. Those in the left column are to be recognized; those in the right column are to be considered optional. The Latin equivalents are given in parentheses. Subspecies ( Subspecies ) Species ( Species ) Subgenus ( Subgenus ) Genus ( Genus ) Tribe ( Tribus ) Family ( Familia ) Suborder ( Subordo ) Order ( Ordo ) Subclass ( Subclassis ) Class ( Classis ) Rule 5b The taxonomic categories above and including subspecies, which are covered by these Rules, are given below in ascending taxonomic rank. Those in the left column should be recognized; those in the right column should be considered optional. The Latin equivalents are given in parentheses. Subspecies ( Subspecies ) Species ( Species ) Subgenus ( Subgenus ) Genus ( Genus ) Tribe ( Tribus ) Family ( Familia ) Suborder ( Subordo ) Order ( Ordo ) Subclass ( Subclassis ) 16 Words from languages other than Latin or Greek should be avoided as parts of genus or subgenus names as long as equivalents exist in Latin or Greek or can be constructed by combining word elements from these two languages. Exceptions can be made for names derived from typical local items such as food, drink or geographical localities for which no Latin or Greek names exist, or for names based on acronyms. As from January 2001, newly proposed names must not be later homonyms of names in use in botany or zoology (see Principle 2). Castellani and Chalmers 1919 (Approved Lists 1980); arbitrary name, Cedecea Grimont et al. 1981. As from 1 January 2001, newly proposed names must not be later homonyms of names with standing in botanical or zoological nomenclature [see Principle 2 and Rule 51b(5)]. Recommendation 10a The following Recommendations apply when forming new generic or subgeneric names: (1) Refrain from naming genera and subgenera after persons unconnected with microbiology or, at least, with natural science. (2) Give a feminine form to all personal generic and subgeneric names, whether they commemorate a man or a woman (see Rule 63). Recommendation 10a The following recommendations apply when forming new generic or subgeneric names. (1) Refrain from naming genera and subgenera after persons unconnected with microbiology or at least with natural science. (2) Give a feminine form to all personal generic and subgeneric names, whether they commemorate a man or a woman (see Appendix 9). Rule 10b Generic and subgeneric names are subject to the same Rules and Recommendations, except that Rule 10c applies only to subgeneric names. Rule 10b Generic and subgeneric names are subject to the same Rules and Recommendations, except that Rule 10c applies only to subgeneric names. Rule 10c Rule 10c 17 The name of a subgenus, when included with the name of a species, is placed in parentheses along with the abbreviation “subgen.” between the generic name and specific epithet. When included, the citation should be inserted before closure of the parentheses. Example: Acetobacter (subgen. Gluconoacetobacter) liquefaciens or Acetobacter (subgen. Gluconoacetobacter Yamada and Kondo 1985) liquefaciens (Asai 1935) Yamada and Kondo 1985. The name of a subgenus, when included with the name of a species, is placed in parentheses along with the abbreviation “subgen.” between the generic name and specific epithet. When included, the citation is inserted before closure of the parentheses. Example: Acetobacter (subgen. Gluconoacetobacter) liquefaciens or Acetobacter (subgen. Gluconoacetobacter Yamada and Kondo 1985) liquefaciens (Asai 1935) Gosselé et al. 1983. Rule 11 Editorial Note. The former Rule 11 has been deleted. This rule only remains here as a placeholder in order to avoid renumbering Rules 12 and above. Rule 11 should not be cited. Rule 11 Editorial Note. The former Rule 11 has been deleted. This rule only remains here as a placeholder in order to avoid renumbering Rules 12 and above. Rule 11 should not be cited. Names of Species Names of Species Rule 12a The name of a species is a binary combination consisting of the name of the genus followed by a single specific epithet. If a specific epithet is formed from two or more words, then the words are to be joined. If the words were not joined at the time of valid publication, then the epithet is not to be rejected but the form is to be corrected by joining the words, which can be done by any author. If an epithet has been hyphenated, the parts should be joined. Such corrections of an epithet do not affect the status and date of valid publication of the name. Rule 12a The name of a species is a binary combination consisting of the name of the genus followed by a single specific epithet. If a specific epithet is formed from two or more words, then the words are to be joined. If the words were not joined at the time of valid publication, then the epithet is not to be rejected or replaced for this reason but the form is to be corrected by joining the words, which can be done by any author. If an epithet has been hyphenated, the parts must be joined. Such corrections of an epithet do not affect the status and date of valid publication of the name. 18 Example: Nocardia otitidis-caviarum has been corrected to Nocardia otitidiscaviarum, or Propionibacterium acidi-propionici has been corrected to Propionibacterium acidipropionici, or Treponema paraluis-cuniculi has been corrected to Treponema paraluiscuniculi. Example: Nocardia otitidis-caviarum (sic) Snijders 1924 (Approved Lists 1980) has been corrected to Nocardia otitidiscaviarum corrig. Snijders 1924 (Approved Lists 1980). Rule 12b No specific or subspecific epithets within the same genus may be the same if based on different types (see Rules 13c, 40d and Section 9). Example: Bacillus pallidus Scholz et al. 1988 is based on the nomenclatural type, strain H12; the specific epithet pallidus cannot be used for Bacillus pallidus Zhou et al. 2008, another bacterium whose name is based on a different type. Rule 12b No specific or subspecific epithets within the same genus may be the same if based on different types (see Rules 13c, 40d and Section 9). Example: Bacillus pallidus Scholz et al. 1988 is based on the nomenclatural type, strain H12; the specific epithet pallidus must not be used for Bacillus pallidus Zhou et al. 2008, another bacterium whose name is based on a different type. Rule 12c A specific epithet may be taken from any source and may even be composed arbitrarily. Example: thetaiotaomicron in Bacteroides thetaiotaomicron derived from a combination of the Greek letters theta, iota and omicron. Words from languages other than Latin or Greek should be avoided as parts of a specific epithet as long as equivalents exist in Latin or Greek or can be constructed by combining word elements from these two languages. Exceptions can be made for names derived from typical local items, such as food, drink or geographical localities for which no Latin or Greek names exist or for names based on acronyms. Rule 12c A specific epithet may be taken from any source and may even be composed arbitrarily. Example: thetaiotaomicron in Bacteroides thetaiotaomicron derived from a combination of the Greek letters theta, iota and omicron. 19 Example: safensis in Bacillus safensis , arbitrarily derived from SAF (the spacecraft-assembly facility at the Jet Propulsion Laboratory, Pasadena, CA, USA). A specific epithet must be treated in one of the three following ways: (1) As an adjective in the singular number in the nominative case that must agree in gender with the generic name. Example: aureus in Staphylococcus aureus. (2) As a noun in apposition in the nominative case. Example: Blautia obeum. (3) As a noun in the genitive case. Example: coli in Escherichia coli. Example: safensis in Bacillus safensis Satomi et al. 2006 , arbitrarily derived from SAF (the spacecraft-assembly facility at the Jet Propulsion Laboratory, Pasadena, CA, USA). A specific epithet must be treated in one of the three following ways. (1) As an adjective in the singular number in the nominative case that must agree in gender with the generic name. Example: aureus in Staphylococcus aureus Rosenbach 1884 (Approved Lists 1980). (2) As a noun in apposition in the nominative case. Example: obeum in Blautia obeum (Moore et al. 1976) Lawson and Finegold 2015. (3) As a noun in the genitive case. Example: coli in Escherichia coli (Migula 1895) Castellani and Chalmers 1919 (Approved Lists 1980). Recommendation 12c Authors should attend to the following Recommendations, and those of Recommendation 6, when forming specific epithets. Recommendation 12c Authors should attend to the following Recommendations, and those of Recommendation 6, when forming specific epithets. 20 (1) Choose a specific epithet that gives some indication of a property or of the source of the species. (2) Avoid those that express a character common to all, or nearly all, the species of a genus. (3) Specific epithets should not honour the author or co-authors of the proposed species or subspecies, or any persons not connected with microbiology or at least with natural science. (4) Avoid in the same genus epithets which are very much alike, especially those that differ only in their last letters (see Rule 56a(4)). (5) Avoid the use of the genitive and the adjectival forms of the same specific epithet to refer to two different species of the same genus (see Rule 63). (6) If an ordinal adjective used for enumeration is chosen, then they may include numbers up to ten. Example: primus, secundus. (1) Choose a specific epithet that gives some indication of a property or of the source of the species. (2) Avoid those that express a character common to all, or nearly all, the species of a genus. (3) Specific epithets should not honour the author or co-authors of the proposed species or subspecies, or any persons not connected with microbiology or at least with natural science. (4) Avoid in the same genus epithets that are very much alike, especially those that differ only in their last letters [see Rule 56a(4)]. (5) Avoid the use of the genitive and the adjectival forms of the same specific epithet to refer to two different species of the same genus (see Appendix 9). (6) If an ordinal adjective used for enumeration is chosen, then they may include numbers up to ten. Example: primus, secundus. Names of Subspecies Names of Subspecies Rule 13a The name of a subspecies is a ternary combination consisting of the name of a genus followed by a specific epithet, the abbreviation “subsp.” (subspecies), and finally the subspecific epithet. Rule 13a The name of a subspecies is a ternary combination consisting of the name of a genus followed by a specific epithet, the abbreviation “subsp.” (subspecies), and finally the subspecific epithet. 21 Example: Bacillus s ubtilis subsp. spizizenii Nakamura et al. 1999. Example: Bacillus subtilis subsp. spizizen ii Nakamura et al. 1999. Rule 13b A subspecific epithet is formed in the same way as a specific epithet. When adjectival in form, it agrees in gender with the generic name. Rule 13b A subspecific epithet is formed in the same way as a specific epithet. When adjectival in form, it agrees in gender with the generic name. Example: Acetobacter pasteurianus subsp. paradoxus (Frateur 1950) De Ley and Frateur 1974 (Approved Lists 1980). Rule 13c No two subspecies within the same species or within the same genus may bear the same subspecific epithet (see also Rules 12b and 40d). Rule 13c No two subspecies within the same species or within the same genus may bear the same subspecific epithet (see also Rules 12b and 40d). Example: The name Staphylococcus cohnii subsp. urealyticus corrig. Kloos and Wolfshohl 1991 must be replaced with a different epithet because the epithet urealyticus was already used for another subspecies Staphylococcus capitis subsp. urealyticus corrig. Bannerman and Kloos 1991. Rule 13d A subspecies that includes the type of the species must bear the same epithet as the species (see also Rules 40d and 45). Rule 13d A subspecies that includes the type of the species must bear the same epithet as the species (see also Rules 40d and 45). Example: Bacillus subtilis subsp. subtilis (Ehrenberg 1835) Nakamura et al. 1999. Names of Infrasubspecific Subdivisions Names of Infrasubspecific Subdivisions 22 Rule 14a The designations of the various taxa below the rank of subspecies are not subject to the Rules and Recommendations of this Code (for advice on their nomenclature, see Appendix 10). Rule 14a The designations of the various taxa below the rank of subspecies are not subject to the Rules and Recommendations of this Code (for advice on their nomenclature, see Appendix 10). Rule 14b A Latin or latinized infrasubspecific designation may be elevated by a subsequent author to the status of a subspecies or species name, providing that the resulting name is in conformity with the Rules. If so elevated, for purposes of priority, it ranks from its date of elevation and is attributed to the author(s) who elevated it, provided that the author(s) who elevated it observe(s) Rule 27. Example: Pseudomonas cannabina (ex Šutič and Dowson 1959) Gardan et al. 1999; elevation of Pseudomonas syringae pathovar Cannabina of (Šutič and Dowson 1959) Young et al. 1978 by Gardan et al. [4]. Rule 14b A Latin or Latinized infrasubspecific designation may be elevated by (a) subsequent author(s) to the status of a subspecies or species name, provided that the author(s) who elevated it observe(s) Rule 27. If so elevated, for purposes of priority, it ranks from its date of elevation and is attributed to the author(s) who elevated it. Example: Pseudomonas cannabina (ex Šutič and Dowson 1959) Gardan et al. 1999; elevation of Pseudomonas syringae pathovar Cannabina of (Šutič and Dowson 1959) Young et al. 1978 by Gardan et al. Section 4. Nomenclatural Types and Their Designation Section 4. Nomenclatural Types and Their Designation General General Rule 15 A taxon consists of one or more elements. For each named taxon of the various taxonomic categories (listed below), there shall be designated a single nomenclatural type. The nomenclatural type, referred to in this Code as “type”, is that element of the taxon with which the name is permanently Rule 15 A taxon consists of one or more elements. For each named taxon of the various taxonomic categories (listed below), there shall be designated a single nomenclatural type. The nomenclatural type, referred to in this Code as “type”, is that element of the taxon with which the name is 23 associated, whether as a correct name or as a synonym. The nomenclatural type is not necessarily the most typical or representative element of the taxon. The types are dealt with in Rules 16–22. Types of the various taxonomic categories are presented in Table 2. Table 2. Taxonomic Categories and their Types Taxonomic category Type Subspecies Species Designated strain; in special cases the place of the type strain may be taken by a description, preserved specimen, or an illustration (see Rule 18a(1)) Subgenus Genus Designated species Tribe Family Suborder Order Subclass Class Phylum Kingdom Genus on whose name the name of the higher taxon is based Domain One of the contained genera permanently associated, whether as a correct name or as a synonym. The nomenclatural type is not necessarily the most typical or representative element of the taxon. The types are dealt with in Rules 16–22. Types of the various taxonomic categories are presented in Table 2. Table 2. Taxonomic Categories and their Types Taxonomic category Type Subspecies Species Designated strain; in special cases the place of the type strain may be taken by a description, preserved specimen, or an illustration [see Rule 18a(1)] Subgenus Genus Designated species Tribe Family Suborder Order Subclass Class Phylum Kingdom Genus on whose name the name of the higher taxon is based Domain One of the contained genera Rule 16 The type of a taxon must be designated by the author(s) at the time the name of the taxon is published in the IJSEM (see Rules 15, 18a, b, f, 20a-c, 21a, 22, Rule 16 The type of a taxon must be designated by the author(s) at the time the name of the taxon is published in the IJSEM [see Rules 15, 18a, b, f, 20a-c, 24 27(3)), unless the type of the taxon can be inferred according to Rules 20c, 20e, 21a, 21b or 22. Note. Authors who intend to publish the name in the IJSEM with reference to a description or listing of the properties of the taxon that has appeared in an effective publication under Rule 27(2) must also designate the type when publishing that description. Note. If a type has not been designated in the effective publication, then the type must be designated at the time of publication in IJSEM, in accordance with the Rules of this Code. 18a, 18b, 20a, 20b, 21a, 22, 27(3 )], unless the type of the taxon can be inferred according to Rules 20c, 21a, 21b or 22 paragraph 1. Note 1. Authors who intend to publish a name in the IJSEM with reference to a description or listing of the properties of the taxon that has appeared in an effective publication under Rule 27(2) must also designate the type when publishing that description. Note 2. If a type has not been designated in the effective publication, then the type must be designated at the time of publication in IJSEM, in accordance with the Rules of this Code. Note 3. A type designated by the authors, or designated by the authors and replaced according to Rule 22 paragraph 2, or not designated by the authors and inferred as indicated above must be accepted, unless it is replaced in accordance with Rules 18c, 18f, 18g or 37a(2). Rule 17 The type determines the application of the name of a taxon if the taxon is subsequently divided or united with another taxon. Example: Ash et al. [9] proposed that the genus Bacillus be divided into the genera Bacillus and Paenibacillus, and the genus which contained the type species Bacillus subtilis must be named Bacillus. Rule 17 The type determines the application of the name of a taxon if the taxon is subsequently divided or united with another taxon. Example: Ash et al. [6] proposed that the genus Bacillus Cohn 1872 (Approved Lists 1980) be divided into the genera Bacillus and Paenibacillus Ash et al. 1994 and the genus that contained the type species Bacillus subtilis (Ehrenberg 1835) Cohn 1872 (Approved Lists 1980) must be named Bacillus. Type of a Species or Subspecies Type of a Species or Subspecies 25 Rule 18a Whenever possible, the type of a species or subspecies is a designated strain. The type strain is made up of living cultures of an organism, which are descended from a strain designated as the nomenclatural type. The strain should have been maintained in pure culture and its characters should agree closely to its characters with those in the original description (see Chapter 4C). The type strain may be designated in various ways (see Rules 18b, 18c, and 18d). (1) Until 31 December 2000, where a type strain has not so far been maintained in laboratory cultures or for which a type strain does not exist, a description, preserved specimen, or illustration (see also Rule 18f) may be designated as the type. Example: Non-cultivated, Oscillospira guilliermondii Chatton and Perard 1913. (2) As from 1 January 2001, no further descriptions, preserved (non-viable) specimens, or illustrations may be designated as the type. This does not affect nomenclatural types designated under Rule 18a(1) until 31 December 2000. (3) For species (or subspecies) of Cyanobacteria described under the provisions of the International Code of Nomenclature for algae, fungi, and Rule 18a Whenever possible, the type of a species or subspecies is a designated strain. The type strain is made up of living cultures of an organism, which are descended from a strain designated as the nomenclatural type. The strain should have been maintained in pure culture and should agree closely to its characters with those in the original description. The type strain may be designated in various ways (see Rules 18b, 18c, and 18d). (1) Until 31 December 2000, wherein a type strain has not so far been maintained in laboratory cultures or for which a type strain does not exist, a description, preserved specimen, or illustration (see also Rule 18f) may be designated as the type. Example: Non-cultivated, Oscillospira guilliermondii Chatton and Perard 1913. (2) As from 1 January 2001, no further descriptions, preserved (nonviable) specimens, or illustrations may be designated as the type. This does not affect nomenclatural types designated under Rule 18a(1) until 31 December 2000. Examples: (a) Pure culture, Thiocystis cadagnonensis Peduzzi et al. 2011; (b) pure culture, Spiribacter salinus León et al. 2014; (c) co-culture with host: Nanobdella aerobiophila Kato et al. 2022. (3) For species (or subspecies) of Cyanobacteria described under the provisions of the International Code of Nomenclature for algae, fungi, and 32 Type of a Taxon from Genus to Order (Tribe, Family, Suborder, and Order) Type of a Taxon from Genus to Order (Tribe, Family, Suborder, and Order) Rule 21a The nomenclatural type (see Rule 15) of a taxon above genus, up to and including order, is the included genus with a validly published and legitimate name on which the name of the relevant taxon is based. One taxon of each category must include the type genus. The names of the taxa which include the type genus must be formed by the addition of the appropriate suffix to the stem of the name of the type genus (see Rule 9). Example: Order, Pseudomonadales; suborder, Pseudomonadineae; family, Pseudomonadaceae; tribe, Pseudomonadeae; type genus, Pseudomonas. Rule 21a The nomenclatural type (see Rule 15) of a taxon above genus, up to and including order, is the included genus with a validly published and legitimate name on which the name of the relevant taxon is based. One taxon of each category must include the type genus. The names of the taxa that include the type genus must be formed by the addition of the appropriate suffix to the stem of the name of the type genus (see Rule 9). Example: Order, Pseudomonadales Orla-Jensen 1921 (Approved Lists 1980); suborder, Pseudomonadineae Breed et al. 1957 (Approved Lists 1980); family, Pseudomonadaceae Winslow et al. 1917 (Approved Lists 1980); tribe, Pseudomonadeae Kluyver and van Niel 1936 (Approved Lists 1980); type genus, Pseudomonas Migula 1894 (Approved Lists 1980). Rule 21b If the name of a family was not formed in conformity with Rule 21a but its name has been conserved, then the type genus may be fixed by an Opinion of the Judicial Commission. Example: The genus Escherichia is the type genus of the family Enterobacteriaceae (Opinion 15; Judicial Commission, 1958). Rule 21b If the name of a family was not formed in conformity with Rule 21a but its name has been conserved, then the type genus may be fixed by an Opinion of the Judicial Commission. Example: The genus Escherichia Castellani and Chalmers 1919 (Approved Lists 1980) is the type genus of the family Enterobacteriaceae Rahn 1937 (Approved Lists 1980) (Opinion 15). Type of a Taxon Higher than Order Type of a Taxon Higher than Order 33 Rule 22 The type of a phylum is one of the contained genera. If there is only one genus, this becomes the type. If there are two or more genera, the type shall be designated by the author(s) at the time of the proposal of the phylum name, although authors are encouraged to respect priority by considering which genus was described first. If the author(s) designated as the nomenclatural type of a taxon of a rank above genus, up to and including phylum, another taxon above the rank of genus but below the rank of that taxon and contained within that taxon, and if the nomenclatural type of this designated nomenclatural type is a genus with a validly published and legitimate name, then this genus automatically becomes the nomenclatural type of that taxon in place of the designated nomenclatural type. If not designated, the type of a taxon higher than order may be later designated by an Opinion of the Judicial Commission. Rule 22 The type of a domain, kingdom, phylum, class or subclass is one of the contained genera. If only one generic name is validly published, this becomes the type. If two or more genera have validly published names, the type shall be designated by the author(s) at the time of the proposal of the name, although authors are encouraged to respect priority by considering which genus was described first. If the author(s) designated as the nomenclatural type of a taxon of a rank above genus, up to and including domain, another taxon above the rank of genus but below the rank of that taxon and contained within that taxon, and if the nomenclatural type of this designated nomenclatural type is a genus with a validly published and legitimate name, then this genus automatically becomes the nomenclatural type of that taxon in place of the designated nomenclatural type. If not designated, the type of a taxon higher than order may be later designated by an Opinion of the Judicial Commission. Section 5. Priority, Effective and Valid Publication of Names Section 5. Priority, Effective and Valid Publication of Names Rule 23a Each taxon above and including species, up to and including order, with a given circumscription, position, and rank can bear only one correct name, i.e., the earliest that is in accordance with the Rules of this Code. Rule 23a Each taxon with a given circumscription, position, and rank can bear only one correct name, i.e., the earliest that is in accordance with the Rules of this Code. The name of a species is a binary combination of a generic name and specific epithet (see Rule 12a). In a given position, a species can bear only 34 The name of a species is a binary combination of a generic name and specific epithet (see Rule 12a). In a given position, a species can bear only one correct epithet, that is, the earliest that is in accordance with the Rules of this Code. Example: The species Haemophilus pleuropneumoniae bears this name in the genus Haemophilus. When placed in the genus Actinobacillus, it bears the name Actinobacillus pleuropneumoniae. Note 1. In the case of a species, Rule 23a must be applied independently to the generic name and the specific epithet. The specific epithet remains the same on transfer of a species from one genus to another, except for necessary changes of the gender of adjectives used as specific epithets, i.e., to comply with Rule 12c(1), unless the specific epithet has been previously used in the name of another species or subspecies in the genus to which the species is transferred (see Rule 41a). one correct epithet, that is, the earliest that is in accordance with the Rules of this Code. Example: The species Yersinia philomiragia Jensen et al. 1969 (Approved Lists 1980) bears this name in the genus Yersinia van Loghem 1944 (Approved Lists 1980). When placed in the genus Francisella Dorofeev 1947 (Approved Lists 1980), it bears the name Francisella philomiragia (Jensen et al. 1969) Hollis et al. 1990. Note 1. In the case of a species, Rule 23a must be applied independently to the generic name and the specific epithet. The specific epithet remains the same on transfer of a species from one genus to another, except for necessary changes of the gender of adjectives used as specific epithets, i.e., to comply with Rule 12c(1), unless the specific epithet has been previously used in the name of another species or subspecies in the genus to which the species is transferred (see Rule 41a). Example: Marinobacterium georgiense González et al. 1997 and Pseudomonas iners Iizuka and Komagata 1964 (Approved Lists 1980) were proposed as heterotypic synonyms by Satomi et al. (2002), who suggested the use of the name Marinobacterium georgiense González et al. 1997. However, the epithet in Pseudomonas iners Iizuka and Komagata 1964 (Approved Lists 1980) has priority over the epithet in Marinobacterium georgiense González et al. 1997. This necessitates the proposal of the new combination Marinobacterium iners (Iizuka and Komagata 1964) Tindall 2020 as the earlier heterotypic synonym of Marinobacterium georgiense González et al. 1997. Note 2. The name of a subspecies is a ternary combination of a generic name, a specific epithet, and a subspecific epithet (see Rule 13c). In a given 35 Note 2 . The name of a subspecies is a ternary combination of a generic name, a specific epithet, and a subspecific epithet (see Rule 13c). In a given position, a subspecies can bear only one correct subspecific epithet, i.e., the earliest that is in accordance with the Rules of this Code. In the case of a subspecies, Rule 23a must be applied independently to the specific and subspecific epithets. The subspecific epithet remains the same on transfer of a subspecies from one species to another, except for necessary changes of the gender of adjectives used as specific epithets, i.e., to comply with Rule 12c(1), unless the subspecific epithet has been previously used in the name of another species or subspecies in the genus to which the subspecies is to be transferred (see Rule 41a). Note 3. The date from which all priorities were determined under the previous revisions of the Code was 1 May 1753. After 1 January 1980, under Rule 24a, all priorities date from 1 January 1980 (see also Rule 24b). Note 4. The Judicial Commission may make exceptions to Rule 23a by the addition of names to the list of conserved names (nomina conservanda) or to the list of rejected names (nomina rejicienda) (see Appendix 4). The Judicial Commission may correct the Approved Lists (see Rule 24a). (1) By conserved name (nomen conservandum) is meant a name which must be used instead of all earlier synonyms and homonyms. By rejected name position, a subspecies can bear only one correct subspecific epithet, i.e., the earliest that is in accordance with the Rules of this Code. In the case of a subspecies, Rule 23a must be applied independently to the specific and subspecific epithets. The subspecific epithet remains the same on transfer of a subspecies from one species to another, except for necessary changes of the gender of adjectives used as specific epithets, i.e., to comply with Rule 12c(1), unless the subspecific epithet has been previously used in the name of another species or subspecies in the genus to which the subspecies is transferred (see Rule 41a). Note 3. The date from which all priorities were determined under the previous revisions of the Code was 1 May 1753. After 1 January 1980, under Rule 24a, all priorities date from 1 January 1980 (see also Rule 24b). Note 4. The Judicial Commission may make exceptions to Rule 23a by the addition of names to the list of conserved names (nomina conservanda) or to the list of rejected names (nomina rejicienda) (see Appendix 4). The Judicial Commission may correct the Approved Lists (see Rule 24a). The Judicial Commission may, if presented with new evidence or a new rationale, reconsider decisions of rejecting or conserving a name or epithet by revisiting a previously issued Opinion. Example: Opinion 75 was revisited, and Methanothrix Huser et al. 1983 and Methanothrix soehngenii Huser et al. 1983 are not to be considered as rejected names. (1) A conserved name (nomen conservandum) is a name that must be used instead of all earlier synonyms and homonyms. A rejected name (nomen rejiciendum) is a name that must not be used to designate any taxon. Only the Judicial Commission can conserve or reject names (see also Rules 56a 36 ( nomen rejiciendum ) is meant a name which must not be used to designate any taxon. Only the Judicial Commission can conserve or reject names (see also Rules 56a and 56b). (2) Opinions on the conservation or rejection of names, issued by the Judicial Commission, are published with other Opinions in the IJSEM. Opinions are numbered serially. Note 5. Names may be: validly published—the name is included in an effective publication and is accompanied by a description of the taxon or a reference to a description and certain other requirements (see Rules 27–32); legitimate—validly published and in accordance with the Rules; illegitimate—validly published and contrary to the Rules; correct—the name which must be adopted for a taxon under the Rules. and 56b). Alternatively, a name can be c onserved to change its nomenclatural type [see Rule 37a(2)]. (2) Opinions on the conservation or rejection of names, issued by the Judicial Commission, are published with other Opinions in the IJSEM. Opinions are numbered serially. Note 5. Names may be: validly published– the name is included in an effective publication and is accompanied by a description of the taxon or a reference to a description and certain other requirements (see Rules 27– 32); legitimate—validly published and in accordance with the Rules; illegitimate—validly published and contrary to the Rules a Rule; correct– the name that must be adopted for a taxon under the Rules. Rule 23b The date of a name or epithet is that of its valid publication. For purposes of priority, only legitimate names and epithets are taken into consideration (see Rules 32b and 54). Rule 23b The date of a name or epithet is that of its valid publication. For purposes of priority, only legitimate names and epithets are taken into consideration (see Rules 32b and 54). Rule 24a Valid publication of names (or epithets) that are governed by the Rules of this Code dates from the dates of publication of the Code. Priority of publication dates from 1 January 1980. On that date, all names published prior to 1 January 1980 and included in the Approved Lists of Bacterial Names are treated, for nomenclatural purposes, as though they had Rule 24a Valid publication of names (or epithets) that are governed by the Rules of this Code dates from the dates of publication of the Code. Priority of publication dates from 1 January 1980. On that date, all names published prior to 1 January 1980 and included in the Approved Lists of Bacterial Names are treated, for nomenclatural purposes, as though they 37 been validly published for the fi rst time on that date, the existing types being retained (but see Rule 24b). Priority of publication for names of Cyanobacteria validly published under the provisions of the International Code of Nomenclature for algae, fungi, and plants [7] is determined by Article 13.1 of that Code. Note 1. Names of prokaryotes in the various taxonomic ranks published until 31 December 1977 were assessed by the Judicial Commission, with the assistance of taxonomic experts. Lists of names were prepared together with the names of the author(s) who originally proposed the names. These Approved Lists of Bacterial Names were approved by the ICSB and published in the IJSB on 1 January 1980. Names validly published between 1 January 1978 and 1 January 1980 were included in the Approved Lists of Bacterial Names (see Appendix 2). No further names will be added to the Approved Lists. Those names validly published prior to 1 January 1980 but not included in the Approved Lists have no further standing in nomenclature. They were not added to the lists of nomina rejicienda and are thus available for reuse in the naming of new taxa. The reuse of a particular name cannot be recommended if such reuse is likely to result in confusion due to previous or continuing use of the name as a synonym, a strain designation, or for other reasons. The Approved Lists of Bacterial Names contain for each name a reference to a description that has appeared in an effective publication and the type, whenever possible. In the case of species or subspecies, if a type strain is available, it is listed by its designation and the culture collection(s) from which it may be obtained is indicated. If such a strain is not available, a reference strain or reference material is indicated, if possible. Neotypes may be had been validly published for the first time on that date, the existing types being retained (but see Rule 24b). Priority of publication for names of Cyanobacteria validly published under the provisions of the International Code of Nomenclature for algae, fungi, and plants is determined by Article 13.1 of that Code. Note 1. Names of prokaryotes in the various taxonomic ranks published until 31 December 1977 were assessed by the Judicial Commission, with the assistance of taxonomic experts. Lists of names were prepared together with the names of the author(s) who originally proposed the names. These Approved Lists of Bacterial Names were approved by the ICSB and published in the IJSB on 1 January 1980. Names validly published between 1 January 1978 and 1 January 1980 were included in the Approved Lists of Bacterial Names (see Appendix 2). No further names will be added to the Approved Lists. Those names validly published prior to 1 January 1980 but not included in the Approved Lists have no further standing in nomenclature. They were not added to the lists of nomina rejicienda and are thus available for reuse in the naming of new taxa. The reuse of a particular name cannot be recommended if such reuse is likely to result in confusion due to previous or continuing use of the name as a synonym, a strain designation, or for other reasons. The Approved Lists of Bacterial Names contain for each name a reference to a description that has appeared in an effective publication and the type, whenever possible. In the case of species or subspecies, if a type strain is available, it is listed by its designation and the culture collection(s) from which it may be obtained is indicated. If such a strain is not available, a reference strain or reference material is indicated, if possible. Neotypes 38 proposed, in conformity with Rule 18c, on such lists. (For citation of names on the Approved Lists, see Rules 33b and 34a.) Note 2. These Approved Lists may contain more than one name attached to the same type (homotypic synonyms) since the names on the list represent names that were accepted in prokaryotic nomenclature and taxonomy at the time of publication of the Approved Lists and represented the views of microbiologists who held different taxonomic opinions. Note 3. Synonyms may be homotypic synonyms (i.e., more than one name has been associated with the same type) or heterotypic synonyms (i.e., different names have been associated with different types that, in the opinion of the microbiologist concerned, belong to the same taxon). The synonym first published is known as the earlier synonym, and subsequently published synonyms are known as later synonyms. Note 4. Homotypic synonyms were previously referred to as objective synonyms. Heterotypic synonyms were previously referred to as subjective synonyms. Earlier synonyms were previously referred to as senior synonyms. Later synonyms were previously referred to as junior synonyms. Publication of homotypic synonyms in the Approved Lists does not affect prokaryotic nomenclature any more than does the valid publication of homotypic synonyms in currently published prokaryotic taxonomic literature. Examples: Homotypic synonyms – Pseudomonas mallei (Zopf 1885) Redfearn et al. 1966 (Approved Lists 1980) and Burkholderia mallei (Zopf 1885) Yabuuchi et al. 1993 are based on the same type. Heterotypic may be proposed, in conformity with Rule 18c on such lists. (For citation of names on the Approved Lists, see Rules 33b and 34a.) Note 2. These Approved Lists may contain more than one name attached to the same type (homotypic synonyms) since the names on the list represent names that were accepted in prokaryotic nomenclature and taxonomy at the time of publication of the Approved Lists and represented the views of microbiologists who held different taxonomic opinions. Note 3. Synonyms may be homotypic synonyms (i.e., more than one name has been associated with the same type) or heterotypic synonyms (i.e., different names have been associated with different types that, in the opinion of the microbiologist concerned, belong to the same taxon). The synonym first published is known as the earlier synonym, and subsequently published synonyms are known as later synonyms. Note 4. Homotypic synonyms were previously referred to as objective synonyms. Heterotypic synonyms were previously referred to as subjective synonyms. Earlier synonyms were previously referred to as senior synonyms. Later synonyms were previously referred to as junior synonyms. Publication of homotypic synonyms in the Approved Lists does not affect prokaryotic nomenclature any more than does the valid publication of homotypic synonyms in currently published prokaryotic taxonomic literature. Examples: Homotypic synonyms – Pseudomonas mallei (Zopf 1885) Redfearn et al. 1966 (Approved Lists 1980) and Burkholderia mallei (Zopf 1885) Yabuuchi et al. 1993 are based on the same type. Heterotypic 39 synonyms – Kelly and Wood [11] regard Thiobacillus concretivorus Parker 1945 as a heterotypic synonym of Thiobacillus thiooxidans Waksman and Joffe 1922. These two species have different types. synonyms – Kelly and Wood [10] regard Thiobacillus concretivorus Parker 1945 (Approved Lists 1980) as a heterotypic synonym of Thiobacillus thiooxidans Waksman and Joffe 1922 (Approved Lists 1980). These two species have different types. Homonyms are names published for taxa in the same category that are spelled exactly the same (apart from orthographic or grammatical corrections, as detailed in Section 9), but which are based on different types. The first homonym published is known as the earlier homonym, while those published subsequently are known as later homonyms. Note 5. A name contained in an Approved List may have a basonym (Rule 34a). If so, that basonym is also the basonym of any subsequent new combination or nomen novum, even if the basonym is not included in an Approved List and is not validly published. Example. The basonym of Janthinobacterium lividum (Eisenberg 1891) De Ley et al. 1978 (Approved Lists 1980) is “Bacillus lividus” Eisenberg 1891. Rule 24b When the nomenclatural types of two or more taxa that are considered to be heterotypic synonyms, priority of the names or epithets and consequently which are the correct names or correct epithets are determined as follows (see also Rule 23a and 23b): (1) If two or more names or epithets based on different nomenclatural types compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and if all names or epithets were included on an Approved List, priority shall be determined by the date of the name or epithet Rule 24b When the names of two or more taxa are considered to be heterotypic synonyms, priority of the names or epithets and consequently which are the correct names or correct epithets are determined as follows (see also Rule 23a and 23b): (1) If two or more names or epithets based on different nomenclatural types compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and if all names or epithets were included on an Approved List, priority shall be determined by the date of the name or 40 given on the Approved List (i.e., before 1 January 1980) unless an earlier name or epithet is illegitimate (see Rule 23b). If two or more names or epithets are of the same date, the author(s) who first unite(s) the taxa has the right to choose one of them, and this choice must be followed. (2) If two or more names or epithets are of the same date, the author who first unites the taxa has the right to choose one of them, and this choice must be followed. If two or more names or epithets based on different nomenclatural types compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and one or more names or epithets appear on an Approved List while the others were otherwise validly published after 1 January 1980, then priority is determined by the date of the name(s) or epithet(s) as given on the Approved List (i.e., before 1 January 1980) and the date of valid publication of the other name(s) or epithet(s) in the IJSB/IJSEM after 1 January 1980 unless an earlier name or epithet is illegitimate (see Rule 23b). If two or more names or epithets are of the same date, the author who first unites the taxa has the right to choose one of them, and this choice must be followed. (3) If two or more names or epithets based on different nomenclatural types that are validly published between 1 January 1980 and 31 December 2020 (and therefore not included on the Approved Lists, 1980, or the Corrigenda, 1984) and compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms), priority is determined by the date of the valid publication (or announcement) of the name or epithet in the IJSB/IJSEM, unless an earlier name or epithet is illegitimate (see Rule 23b). (4) If two names or epithets appear in the same volume of the IJSB/IJSEM but in different articles, priority is determined by page number or the order epithet given on the Approved List (i.e., before 1 January 1980) unless an earlier name or epithet is illegitimate (see Rule 23b). If two or more names or epithets are of the same date, the author who first unites the taxa has the right to choose one of them, and this choice must be followed. (2) If two or more names or epithets based on different nomenclatural types compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and one or more names or epithets appear on an Approved List while the others were otherwise validly published after 1 January 1980, then priority is determined by the date of the name(s) or epithet(s), as given on the Approved List (i.e., before 1 January 1980) and the date of valid publication of the other name(s) or epithet(s) in the IJSB/IJSEM after 1 January 1980, unless an earlier name or epithet is illegitimate (see Rule 23b). If two or more names or epithets are of the same date, the author who first unites the taxa has the right to choose one of them, and this choice must be followed. (3) If two or more names or epithets based on different nomenclatural types that are validly published between 1 January 1980 and 31 December 2020 (and therefore not included on the Approved Lists, 1980, or the Corrigenda, 1984) compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms), priority is determined by the date of the valid publication (or announcement) of the name or epithet in the IJSB/IJSEM unless an earlier name or epithet is illegitimate (see Rule 23b). (4) If two names or epithets appear in the same volume of the IJSB/IJSEM but in different articles, priority is determined by page number or the 41 of article publication; a name or epithet appearing on a lower page number or an article published earlier in the same issue is deemed to have priority. If two or more names or epithets that appear in the same article compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) the author who first unites the taxa has the right to choose one of them, and this choice must be followed. In order to implement Rule 24b (2) and 24b (3) in the fairest manner, as of first January 1988 (Validation List no 24 onwards) names submitted for inclusion in the Validation List will be allocated a number that reflects the date of receipt of the validation request in the form that is accepted for publication. Where names that were included in other printed or electronic publications as effective publications are validly published by announcement on the same Validation List in IJSEM, priority is established by the number allocated on the list. If two or more names or epithets on the same Validation List compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and are attributed the same number (or no number was assigned) the author who first unites the taxa has the right to choose one of them, and this choice must be followed. (5) If two names published after 1 January 2021 in different articles have the same publication date in the IJSEM, priority shall be determined by the date of acceptance for publication. (6) If two names effectively published in other journals are validly published by announcement in the same Validation List in IJSEM, priority is established by the sequence number on the list. order of article publication; a name or epithet appearing on a lower page number or an article published earlier in the same issue is deemed to have priority. If two or more names or epithets that appear in the same article compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) the author who first unites the taxa has the right to choose one of them, and this choice must be followed. In order to implement Rule 24b (2) and 24b (3) in the fairest manner, as of 1st January 1988 (Validation List no 24 onwards), names submitted for inclusion in the Validation List will be allocated a number that reflects the date of receipt of the validation request in the form that is accepted for publication. Wherein names that were included in other printed or electronic publications as effective publications are validly published by announcement on the same Validation List in IJSEM, priority is established by the number allocated on the list. If two or more names or epithets on the same Validation List compete for priority (i.e., the names or combinations are considered to be heterotypic synonyms) and are attributed the same number (or no number was assigned) the author who first unites the taxa has the right to choose one of them, and this choice must be followed. (5) If two names published after 1 January 2021 in different articles have the same publication date in the IJSEM, priority shall be determined by the date of acceptance for publication. (6) If two names effectively published in other journals are validly published by announcement in the same Validation List in IJSEM, priority is established by the sequence number on the list. In order to implement Rule 24b(2) and 24b(3) in the fairest manner, as of 1 January 1988 (Validation List no 24 onwards), names submitted for inclusion in the Validation List will be allocated a number that reflects the date of receipt 48 new species or of the new combination alone does not constitute valid publication of the name of the new genus. Rule 28a Authors validly publishing a new name after 1 January 1980 may revive a name published prior to 1 January 1980 (see Rule 24a) but not listed in one of the Approved Lists of Bacterial Names unless the name is a nomen rejiciendum. The name may be used whether or not the new taxon is related in any way to the taxon to which the name was originally applied. Authority for the name must be claimed by the new authors. If the authors wish to indicate that the name is a revived name and is used to describe a taxon with the same circumscription, position, and rank as that given by the original authors, this may be done by appending the abbreviation “nom. rev.” (revived name) to the name (see Rule 33c). The proposal must contain a brief diagnosis, i.e., a statement or list of features that led the author(s) to conclude that the proposed taxon is sufficiently different from other recognized taxa to justify its revival. The data included in the statement may be taken from the earlier description and may include newer data. The description of the taxon and derivation of the name must conform to the requirements of Rule 27(2). The type must be designated [see Rule 27(3)]. Note 1. A new name which was previously published before 1 January 1980 is considered to be already validly published only if the name was included in the Approved Lists of Bacterial Names. Rule 28a Authors validly publishing a new name after 1 January 1980 may revive a name published prior to 1 January 1980 (see Rule 24a) but not listed in one of the Approved Lists of Bacterial Names unless the name is a nomen rejiciendum. The name may be used whether or not the new taxon is related in any way to the taxon to which the name was originally applied. Authority for the name must be claimed by the new author. If the author wishes to indicate that the name is a revived name and is used to describe a taxon with the same circumscription, position, and rank as that given by the original author, this may be done by appending the abbreviation “nom. rev.” (revived name) to the name (see Rule 33c). The proposal must contain a brief diagnosis, i.e., a statement or list of features that led the author to conclude that the proposed taxon is sufficiently different from other recognized taxa to justify its revival. The data included in the statement may be taken from the earlier description and may include newer data. The description of the taxon and derivation of the name must conform to the requirements of Rule 27(2). The type must be designated [see Rule 27(3)]. Note 1. A new name that was previously published before 1 January 1980 is considered to be already validly published only if the name was included in the Approved Lists of Bacterial Names. 49 Note 2. Since revived names are treated as new names, they require valid publication, and the date of priority of a revived name is that of the publication in the IJSEM (see Rule 27). Note 3. Searching for publication of names and descriptions included in effective publications prior to 1 January 1980 is no longer required. The Approved Lists of Bacterial Names form the foundation of a new prokaryotic nomenclature and taxonomy. Note 2. Since revived names are treated as new names, they require valid publication, and the date of priority of a revived name is that of the publication in the IJSEM (see Rule 27). Note 3. Searching for publication of names and descriptions included in effective publications prior to 1 January 1980 is no longer required. The Approved Lists of Bacterial Names form the foundation of a new prokaryotic nomenclature and taxonomy. Rule 28b A name or epithet is not validly published in the following circumstances: (1) It was not accepted at the time of publication by the author(s) who published it. Example: Muellerina de Petschenko 1910 (Opinion 10; Judicial Commission). Names or epithets published with a question mark or other indication of taxonomic doubt, yet accepted by the author(s), are not validly published. (2) It was merely proposed in anticipation of the future acceptance of the taxon concerned or the acceptance of a particular circumscription, position, or rank for the taxon that is being named or in anticipation of the future discovery of some hypothetical taxon. Examples: (a) Clostridium Fischer 1895 (Opinion 20; Judicial Commission); (b) Corynebactenum hemophilum Svendsen et al. 1947. “Its haemophilic properties might be used in coining a name, and the name Corynebacterium hemophilum is suggested in case further investigation should justify its rank as a species”. Rule 28b A name or epithet is not validly published in the following circumstances: (1) It was not accepted at the time of publication by the author(s) who published it. Names or epithets published with a question mark or other indication of taxonomic doubt, yet accepted by the author(s), are also not validly published. (2) It was merely proposed in anticipation of the future acceptance of the taxon concerned or the acceptance of a particular circumscription, position, or rank for the taxon that is being named or in anticipation of the future discovery of some hypothetical taxon. Examples: (a) Clostrinium Fischer 1895 (Opinion 20; not: Clostridium); (b) Corynebacterium hemophilum Svendsen et al. 1947. “Its haemophilic properties might be used in coining a name, and the name Corynebacterium hemophilum is suggested in case further investigation should justify its rank as a species”. 50 (3) It was mentioned incidentally. Incidental mention of a new name means mention by authors who do not clearly state or indicate that they are proposing a new name or combination. Examples: (a) Pseudobacterium Trevisan 1888. (b) Raj [13] stated: “Also, recently another organism tentatively named as Microcyclus marinus was isolated from the ocean.” (3) It was mentioned incidentally. Incidental mention of a new n ame means mention by an author who does not clearly state or indicate that they are proposing a new name or combination. Examples: (a) Pseudobacterium Trevisan 1888. (b) Raj [12] stated: “Also, recently another organism tentatively named as Microcyclus marinus was isolated from the ocean.” Valid Publication of the Name of a Genus or Subgenus, including a Monotypic Genus Valid Publication of the Name of a Genus or Subgenus, including a Monotypic Genus Rule 29 For a generic or subgeneric name to be validly published, it must comply with the following conditions: (1) It must be published in conformity with Rules 27 and 28b. (2) The valid publication of a genus or subgenus name must include one or more new names or combinations validly published, according to Rule 30. (3) A nomenclatural type must be selected at the time of valid publication from one of the species included in the genus or subgenus. In the case of a genus or subgenus containing a single species, that species serves as the type (see Rule 20c). Rule 29 For a generic or subgeneric name to be validly published, it must comply with the following conditions: (1) It must be published in conformity with Rules 27 and 28b. (2) It must include one or more species with validly published names, according to Rule 30. (3) A nomenclatural type must be selected at the time of valid publication from one of the species included in the genus or subgenus. In the case of a genus or subgenus containing a single species, that species serves as the type (see Rule 20c). Example: The genus name Cephaloticoccus Lin et al. 2016 is not validly published, as the authors failed to designate a type species and included more than one species within the genus. 51 Instead of a new description of the genus or subgenus, a citation to a description or the properties of the genus or subgenus in a previous effective publication may be given. The same holds if a genus is lowered in rank to a subgenus, or a subgenus elevated in rank to a genus. In the case of a genus containing a single species, a combined generic and specific description may be given. In the case of a combined generic and specific description for a genus that contains a single species (see Rule 20c), the name of the new taxon is to be given (i.e., the genus name and the species epithet) indicating that it is both a novel genus and a novel species, gen. nov. sp. nov., followed by the etymology of the genus name and species epithet, in conformity with Rules 27 (2a) and (2b). The requirements of Rule 27 (2c), combining the information for the genus and species, are to be followed. At the time of valid publication, the nomenclatural type of the name at the rank of genus and the name at the rank of species must be given, in conformity with Rule 16 and 27 (3). Example: Propioniferax innocua (Pitcher and Collins 1992) Yokota et al. 1994 or Lamprocystis roseopersicina (Kützing 1849) Schroeter 1886 (Approved Lists 1980). Instead of a new description of the genus or subgenus, a citation to a description or the properties of the genus or subgenus in a previous effective publication may be given. The same holds if a genus is lowered in rank to a subgenus or a subgenus elevated in rank to a genus. In the case of a genus containing a single species, a combined generic and specific description may be given. In the case of a combined generic and specific description for a genus that contains a single species (see Rule 20c), the name of the new taxon is to be given (i.e., the generic name and the specific epithet), indicating that it is both a novel genus and a novel species, e.g., gen. nov., sp. nov., followed by the etymology of the generic name and specific epithet, in conformity with Rules 27(2a) and (2b). The requirements of Rule 27(2c), combining the information for the genus and species, are to be followed. At the time of valid publication, the nomenclatural type of the name at the rank of genus and the name at the rank of species must be given, in conformity with Rule 16 and 27(3). Example: Propioniferax innocua (Pitcher and Collins 1992) Yokota et al. 1994 or Lamprocystis roseopersicina (Kützing 1849) Schroeter 1886 (Approved Lists 1980). Recommendation 29 A description of a genus or subgenus should mention the points in which the genus or subgenus differs from related genera or subgenera. Wherein possible, the family to which it belongs should be mentioned. Recommendation 29 A description of a genus or subgenus should mention the points in which the genus or subgenus differs from related genera or subgenera. Wherein possible, the family to which it belongs should be mentioned. Valid Publication of the Name of a Species Valid Publication of the Name of a Species Rule 30 Rule 30 52 For the name of a species to be validly published, it must conform to the following conditions. (1) It must be published in conformity with Rules 27 and 28b. (2) It must be published as a binary combination consisting of a genus name followed by a single species epithet (see Rule 12a). (3) (a) Until 31 December 2000, before valid publication of the name of a new species, a nomenclatural type must be designated according to Rule 18a (1). If the species is cultivated, a culture of the type strain should be deposited in at least one publicly accessible culture collection from which subcultures must be available. The designations allotted to the strain by the culture collections should be quoted in the published description. (b) As of 1 January 2001, the valid publication of the name of a new species, or a new combination previously represented by a viable culture must include the designation of a type strain (see Rule 18a), and a viable culture of that strain must be deposited in at least two publicly accessible culture collections in different countries from which subcultures must be available. The designations allotted to the type strain by the culture collections are to be quoted at the time of valid publication. Evidence must be presented that the cultures are present, viable, and available (see Rule 30 (4)) at the time of publication in the IJSEM. This does not affect nomenclatural types designated until 31 December 2000 under Rule 18a (1) and Rule 30 3(a). For the name of a species to be validly published, it must conform to the following conditions. (1) It must be published in conformity with Rules 27 and 28b. (2) It must be published as a binary combination consisting of a generic name followed by a single specific epithet (see Rule 12a). (3) (a) Until 31 December 2000, before valid publication of the name of a new species, a nomenclatural type must be designated, according to Rule 18a(1). If the species is cultivated, a culture of the type strain should be deposited in at least one publicly accessible culture collection from which subcultures must be available. The designations allotted to the strain by the culture collections should be quoted in the published description. (b) As of 1 January 2001, the valid publication of the name of a new species, or new combination previously represented by a viable culture, must include the designation of a type strain (see Rule 18a), and a viable culture of that strain must be deposited in at least two culture collections in different countries that are publicly accessible at the time of publication in the IJSEM and are able to provide the strain to the scientific community. At least one designation allotted to the type strain by a culture collection must be cited in effective publications. The designations allotted to the type strain by the culture collections are to be quoted at the time of valid publication. Evidence must be presented that the cultures are present, viable, and available [see Rule 30(4)] at the time of publication in the IJSEM. This does not affect nomenclatural types designated until 31 December 2000 under Rule 18a(1) and Rule 30(3)(a). 53 Note. In exceptional cases, such as organisms requiring specialized facilities (e.g., Risk Group/Biological Safety Level 3, high pressure requirements, etc.), exceptions may be made to this Rule. Exceptions will be considered on an individual basis by a committee consisting of the Chair of the ICSP, the Chair of the Judicial Commission and the Editor-in-Chief of the IJSEM. Exceptions will be made known at the time of publication. (4) Organisms deposited in such a fashion that access is restricted, such as safe deposits or strains deposited solely for current patent purposes, may not serve as type strains. Names of taxa of Cyanobacteria validly published in conformity with the Rules of the International Code of Nomenclature for algae, fungi, and plants are also validly published in conformity with the Rules of the International Code of Nomenclature of Prokaryotes (see General Consideration 5). Note. In exceptional cases, such as organisms requiring specialized facilities (e.g., Risk Group/Biological Safety Level 3, high pressure requirements, etc.), exceptions may be made to this Rule. Exceptions will be considered on individual basis by a committee consisting of the Chair of the ICSP, the Chair of the Judicial Commission and the Editor-in-Chief of the IJSEM. Exceptions will be made known at the time of publication. Example: Pyrococcus yayanosii Birren et al. 2011 and Promethearchaeum syntrophicum Imachi et al. 2024. For historical exemptions made as part of the transition to the new rules, see Judicial Opinion 81. (4) Deposits to which access is restricted, such as safe deposits, deposits of strains made solely for current patent purposes, and deposits for which access is not possible until a national authority or any other third party grants permission, may not serve as deposits of type strains. Material Transfer Agreements or other contractual agreements may be attached to deposits of type strains only if these agreements do not prohibit the distribution of subcultures of the deposit for, at least, research for taxonomic purposes. Names of cyanobacterial taxa validly published under the International Code of Nomenclature for algae, fungi, and plants and having one of the categories listed in Rule 5b are also considered validly published under the International Code of Nomenclature of Prokaryotes (see General Consideration 5). Conservation and rejection of cyanobacterial names under the International Code of Nomenclature for algae, fungi, and plants is recognized by the International Code of Nomenclature of Prokaryotes, 54 unless it is overruled by the Judicial Commission. Names of cyanobacterial taxa validly published under the International Code of Nomenclature for algae, fungi, and plants but having other categories are not considered validly published under the International Code of Nomenclature of Prokaryotes but may serve as basonyms. Recommendation 30 Before publication of the name and description of a new species, the examination and description should conform to the current minimal standards (if available) required for the relevant taxon of prokaryote. Note 1. Lists of proposed minimal standards are prepared for prokaryotic taxa by experts for publication in the IJSEM (see Appendix 6). Such standards may include current tests for the establishment of generic identity and for the diagnosis of the species, i.e., an indication of characters which distinguish the species from others. Note 2. The aim of proposed minimal standards is to provide guidance on the description of taxa for taxonomists seeking such advice. However, these standards are not to be applied in a way that contradicts Principle 1 (4). Recommendation 30 Before publication of the name and description of a new species, the examination and description should conform to the current minimal standards (if available) required for the relevant taxon of prokaryote. Note 1. Lists of proposed minimal standards are prepared for prokaryotic taxa by experts for publication in the IJSEM (see Appendix 6). Such standards may include current tests for the establishment of generic identity and for the diagnosis of the species, i.e., an indication of characters that distinguish the species from others. Note 2. The aim of proposed minimal standards is to provide guidance on the description of taxa for taxonomists seeking such advice. However, these standards are not to be applied in a way that contradicts Principle 1 (4). Rule 31a The name of a species or a subspecies is not validly published if the description is demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name of a taxon. Rule 31a The name of a species or a subspecies is not validly published if the description is demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name of a taxon. 55 Examples: (a) ‘ Methanobacillus omelianskii ’ Br yant et al. 1967, whose description included all component species, was treated as a single species, and thus was illegitimate; (b) Syntrophobacter wolinii Boone and Bryant 1984 is legitimate, because the species description applies to one member of the syntrophic association with a hydrogen-producing organism. Examples: (a) ‘ Methanobacillus omelianskii’ Bryant et al. 1967, whose description included all component species, was treated as a single species and, thus, was not validly published; (b) Syntrophobacter wolinii Boone and Bryant 1984 is validly published, because the species description applies to one member of the syntrophic association with a hydrogen-producing organism. Rule 31b The name of a consortium is not regulated by this Code, and such a name is not validly published. Example: ‘Cylindrogloea bacterifera’ Perfiliev 1914. Note. A consortium is an aggregate or association of two or more organisms. Rule 31b The name of a consortium is not regulated by this Code, and such a name is not validly published. Example: ‘Cylindrogloea bacterifera’ Perfiliev 1914. Note. A consortium is an aggregate or association of two or more organisms. Valid Publication of the Name of a Subspecies Valid Publication of the Name of a Subspecies Rule 32a For the name of a subspecies to be validly published, it must conform to the following conditions. (1) It must be published in conformity with Rules 27 and 28b. (2) It must be published as a ternary combination consisting of the generic name followed by a single specific epithet and this, in turn, by a single Rule 32a For the name of a subspecies to be validly published, the name of its species must be validly published and it must conform to the following conditions, unless it is created automatically under Rule 40d. (1) It must be published in conformity with Rules 27 and 28b. (2) It must be published as a ternary combination consisting of the generic name followed by a single specific epithet and this, in turn, by a single 56 subspecific epithet, with the abbreviation “subsp.” between the two epithets to indicate the rank (see Rule 13a). Example: Bacillus subtilis subsp. subtilis. (3) The author(s) must clearly indicate that a subspecies is being named. subspecific epithet, with the abbreviation “subsp.” between the two epithets to indicate the rank (see Rule 13a). Example: Bacillus subtilis subsp. spizizenii Nakamura et al. 1999. (3) The author(s) must clearly indicate that a subspecies is being named. (4) It must be published in conformity with Rules 30(3) and 30(4) after replacing the word 'species' by 'subspecies'. Recommendation 32a Recommendation 30 applies to the name of a subspecies with replacement of the word “species” by the word “subspecies”. Recommendation 32a Recommendation 30 applies to the name of a subspecies with replacement of the word “species” by the word “subspecies”. Publication of a Specific or Subspecific Epithet Publication of a Specific or Subspecific Epithet Rule 32b A specific (or subspecific) epithet is not rendered illegitimate by publication of a species (or subspecies) name in which the generic name is illegitimate (see also Chapter 3, Section 8, and example for Rule 20f). Rule 32b A specific (or subspecific) epithet is not rendered illegitimate by publication of a species (or subspecies) name in which the generic name is illegitimate (see also Chapter 3, Section 8, and example for Rule 20f). Example: The illegitimacy of the generic name Moorella Collins et al. 1994 does not render the epithet stamsii illegitimate in the name Moorella stamsii Alves et al. 2013. Therefore, Neomoorella stamsii (Alves et al. 2013) Gtari and Ventura 2025 was proposed as a replacement for Moorella stamsii, retaining the original epithet. Section 6. Citation of Authors and Names Section 6. Citation of Authors and Names 57 Proposal and Subsequent Citation of the Name of a New Taxon Proposal and Subsequent Citation of the Name of a New Taxon Rule 33a The authors should indicate that a name is being proposed for a new taxon by the addition of the appropriate abbreviation for the category to which the taxon belongs. Note 1. Appropriate abbreviations are: ‘”dom. nov.” for dominium novum, ”regn. nov.” for regnum novum, “phyl. nov.” for phylum novum, “class. nov.” for classis nova, “ord. nov.” for ordo novus, “gen. nov.” for genus novum, “sp. nov.” for species nova, “comb. nov.” for combinatio nova. Similar abbreviations may be formed as required. Note 2. Although words or abbreviations in Latin are usually printed in italics, such abbreviations as the above are frequently printed in Roman or boldface type when they follow a Latin scientific name, in order to differentiate them from the name and draw attention to the abbreviation. Examples: Order, Actinomycetales ord. nov.; family, Actinomycetaceae fam. nov.; genus, Actinomyces gen. nov.; species, Actinomyces bovis sp. nov. Rule 33a The authors must indicate that a name is being proposed for a new taxon and should do so by the addition of the appropriate abbreviation for the category to which the taxon belongs. Note 1. Appropriate abbreviations are include: ‘dom. nov.’ for dominium novum, ‘regn. nov.’ for regnum novum, ‘phyl. nov.’ for phylum novum, ‘class. nov.’ for classis nova, ‘ord. nov.’ for ordo novus, ‘gen. nov.’ for genus novum, ‘sp. nov.’ for species nova, and ‘comb. nov.’ for combinatio nova. Similar abbreviations may be formed as required (see the Table of Appendix 7). Note 2. Although words or abbreviations in Latin are usually printed in italics, such abbreviations as the above are frequently printed in Roman or boldface type when they follow a Latin scientific name, in order to differentiate them from the name and draw attention to the abbreviation. Rule 33b The citation of the name of a taxon that has been proposed previously should include both the name of the author(s) who first published the name and the year of publication. If there are more than two authors of the name, the citation includes only the first author followed by “et al.” and the year. Rule 33b The citation of the name of a taxon that has been proposed previously should include both the name of the author(s) who first published the name and the year of publication. If there are more than two authors of the name, the citation includes only the first author followed by “et al.” and the year. 64 Beijerinck 1898 (Approved Lists 1980) to Acetobacter (Beijerinck 1898) Yamada and Kondo 1985 subgen. nov. Citation of the Name of a Taxon for which the Circumscription Has Been Emended Citation of the Name of a Taxon for which the Circumscription Has Been Emended Rule 35 If an alteration of the diagnostic characters or of the circumscription of a taxon modifies the nature of the taxon, the author(s) responsible may be indicated by the addition to the author citation of the abbreviation ‘‘emend.’’ (emendavit) followed by the name of the author(s) responsible for the change. Example: Rhodopseudomonas Czurda and Maresch 1937 emend. van Niel 1944 (see Opinion 49; Judicial Commission). Rule 35 If an alteration of the diagnostic characters or of the circumscription of a taxon modifies the nature of the taxon, the author(s) responsible may be indicated by the addition to the author citation of the abbreviation ‘‘emend.’’ (emendavit) followed by the name of the author(s) responsible for the change. Example: Rhodopseudomonas Czurda and Maresch 1937 emend. van Niel 1944 (see Opinion 49; Judicial Commission) Moraxella Lwoff 1939 (Approved Lists 1980) emend. Sbissi et al. 2025. Citation of a Name Conserved so as to Exclude the Type Citation of a Name Conserved so as to Exclude the Type Rule 36 A name conserved so as to exclude the type is not to be ascribed to the original author(s), but the author(s) whose concept of the name is conserved must be cited as authority. Example: The original type species of the genus Aeromonas was rejected as a nomen dubium (Opinion 48; Judicial Commission). The generic name Aeromonas is now attributed to Stanier 1943, not to Kluyver and van Niel 1936, and with a new type species, Aeromonas hydrophila. Rule 36 A name conserved so as to exclude the type is not to be ascribed to the original author(s), but the author(s) whose concept of the name is conserved must be cited as authority. Example: The original type species of the genus Aeromonas was rejected as a nomen dubium (Opinion 48; Judicial Commission). The generic name Aeromonas is now attributed to Stanier 1943, not to Kluyver and van Niel 65 1936, and with a new type species, Aeromonas hydrophila ( Chester 1901) Stanier 1943 (Approved Lists 1980). Section 7. Changes in Names of Taxa as a Result of Tra nsference, Union, or Change in Rank Section 7. Changes in Names of Taxa as a Result of Transference, Union, or Change in Rank Rule 37a (1) The name of a taxon must be changed if the nomenclatural type of the taxon is excluded. Example: On transferring the type species of the genus Micropolyspora Lechevalier et al. 1961, Micropolyspora brevicatena Lechevalier et al. 1961 to the genus Nocardia, Goodfellow and Pirouz [17] did not provide a solution for the taxonomic position of Micropolyspora angiospora Zhukova et al. 1968, Micropolyspora faeni Cross et al. 1968, Micropolyspora internatus Agre et al. 1974 and Micropolyspora rectivirgula (Krasil’nikov and Agre 1964) Prauser and Momirova 1970, which they should have removed from the genus Micropolyspora. (2) Retention of a name in a sense that excludes the type can only be effected by conservation and only by the Judicial Commission (see also Rule 23a). At the time of conservation, the new type is established by the Judicial Commission. Rule 37a (1) The name of a taxon must be changed if the nomenclatural type of the taxon is excluded. Example: On transferring the type species of the genus Micropolyspora Lechevalier et al. 1961 (Approved Lists 1980), Micropolyspora brevicatena Lechevalier et al. 1961 (Approved Lists 1980), to the genus Nocardia Trevisan 1889 (Approved Lists 1980), Goodfellow and Pirouz [16] did not provide a solution for the taxonomic position of Micropolyspora angiospora Zhukova et al. 1968 (Approved Lists 1980), Micropolyspora faeni Cross et al. 1968 (Approved Lists 1980), Micropolyspora internatus Agre et al. 1974 (Approved Lists 1980) and Micropolyspora rectivirgula (Krassilnikov and Agre 1964) Prauser and Momirova 1970 (Approved Lists 1980), which they should have removed from the genus Micropolyspora. (2) Retention of a name in a sense that excludes the type can only be effected by conservation and only by the Judicial Commission (see also Rule 23a). At the time of conservation, the new type is established by the Judicial Commission. Examples: The name of the type species of the genus Methanosarcina Kluyver and van Niel 1936 (Approved Lists 1980), Methanosarcina methanica (Smit 1930) Kluyver and van Niel 1936 (Approved Lists 1980), 66 was rejected; the Judicial Commission therefore conserved the genus Methanosarcina, establishing Methanosarcina barkeri Schnellen 1947 (Approved Lists 1980) as the new type species (Opinion 63). Salmonella choleraesuis (Smith 1894) Weldin 1927 (Approved Lists 1980) was replaced by Salmonella enterica (ex Kauffmann and Edwards 1952) Le Minor and Popoff 1987 as the type species of the genus Salmonella Lignieres 1900 (Approved Lists 1980) (Opinion 80). Rule 37b A change in the name of a taxon is not warranted by an alteration of the diagnostic characters or of the circumscription. A change in a name may be required by one of the following. (1) An Opinion of the Judicial Commission [see Rule 37a(2) above]. (2) Transfer of the taxon (see Rule 41). (3) Union with another taxon (Rules 42–44 and 47b). (4) Change of rank (Rules 48, 49, 50a, 50b). Rule 37b A change in the name of a taxon is not warranted by an alteration of the diagnostic characters or of the circumscription. A change in a name may be required by one of the following. (1) An Opinion of the Judicial Commission [see Rule 37a(2) above]. (2) Transfer of the taxon (see Rule 41). (3) Union with another taxon (Rules 42–44 and 47b). (4) Change of rank (Rules 48, 49, 50a, 50b). Rule 38 When two or more taxa of the same rank are united, the name of the taxon under which they are united (and, therefore, the type of the taxon) is chosen by the rule of priority of publication. Example: White [18] united Eberthella Bergey et al. 1923 [19] with Salmonella Lignières 1900 and retained the earlier name, Salmonella. Rule 38 When two or more taxa of the same rank are united, the name of the taxon under which they are united (and, therefore, the type of the taxon) is chosen by the rule of priority of publication. Example: If the orders Bacillales Prévot 1953 (Approved Lists 1980) and Caryophanales Peshkoff 1939 (Approved Lists 1980) are united by placing 67 Note. Eberthella was raised by Bergey et al. [19] to a genus from the subgeneric name, Eberthella Buchanan 1918. If, however, this choice would lead to confusion in prokaryotic nomenclature, the author(s) should refer this matter to the Judicial Commission. Example: Not yet found. their respective type genera, Bacillus Cohn 1872 (Approved Lists 1980) and Caryophanon Peshkoff 1939 (Approved Lists 1980), into the same order, its correct name is Caryophanales Peshkoff 1939 (Approved Lists 1980). Division of a Genus into Multiple Genera or Subgenera, and of a Subgenus into Subgenera Division of a Genus into Multiple Genera or Subgenera, and of a Subgenus into Subgenera Rule 39a If a genus is divided into two or more genera or subgenera, the generic name must be retained for one of these. If the name has not been retained (in a previous publication), it must be re-established under Rule 39b. (See Rule 49 when a subgenus is raised to genus.) Example: Ash et al. [9] proposed that the genus Bacillus be divided into the genera Bacillus and Paenibacillus, and the genus which contained the type species Bacillus subtilis must be named Bacillus. Rule 39a If a genus is divided into two or more genera or subgenera, the generic name must be retained for one of these. If the name has not been retained (in a previous publication), it must be re-established under Rule 39b. (See Rule 49 when a subgenus is raised to genus). Example: Ash et al. [4] proposed that the genus Bacillus Cohn 1872 (Approved Lists 1980) be divided into the genera Bacillus and Paenibacillus Ash et al. 1994, and the genus that contained the type species Bacillus subtilis (Ehrenberg 1835) Cohn 1872 (Approved Lists 1980) must be named Bacillus. Rule 39b When a particular species has been designated as the type, the generic name must be retained for the genus which includes that species. Rule 39b When a particular species has been designated as the type, the generic name must be retained for the genus that includes that species. Rule 39c Rule 39c 68 The provisions of Rules 39a and 39b apply when a subgenus is divided into two or more subgenera, the original subgeneric name being retained for that subgenus which contains the type species. The provisions of Rules 39a and 39b apply when a subgenus is divided into two or more subgenera, the original subgeneric name being retained for that subgenus that contains the type species. Division of a Species into Multiple Species or Subspecies, and of a Subspecies into Multiple Subspecies D ivision of a Species into Multiple Species or Subspecies, and of a Subspecies into Multiple Subspecies Rule 40a When a species is divided into two or more species or subspecies, the specific epithet of the original species must be retained for one of the taxa into which the species is divided or, if the epithet has not been retained (in a previous publication), it must be re-established. (See Rule 50a when a subspecies is elevated to a species). Rule 40a When a species is divided into two or more species or subspecies, the specific epithet of the original species must be retained for one of the taxa into which the species is divided or, if the epithet has not been retained (in a previous publication), it must be re-established. (See Rule 50a when a subspecies is elevated to a species). Examples: When the species Streptococcus parasuis Nomoto et al. 2015 was proposed to harbour several serotypes of Streptococcus suis (ex Elliott 1966) Kilpper-Bälz and Schleifer 1987, the epithet suis was retained for the species containing the type strain of Streptococcus suis. When Corynebacterium diphtheriae (Kruse 1886) Lehmann and Neumann 1896 (Approved Lists 1980) was divided into two subspecies, C. diphtheriae subsp. lausannense subsp. nov. Tagini et al. 2019 was proposed for the other lineage, while C. diphtheriae subsp. diphtheriae (Kruse 1886) Tagini et al. 2019 subsp. nov. was proposed for the lineage that includes the type strain of C. diphtheriae. Rule 40b Rule 40b 69 The specific epithet must be retained for the species or subspecies which includes the type strain. When no type was designated, one must be designated. Example: If the species Bacillus The specific epithet must be retained for the species or subspecies that includes the type strain. When no type was designated, one must be designated. Example: If the species Bacillus subtilis (Ehrenberg 1835) Cohn 1872 (Approved Lists 1980) is divided into subspecies, the subspecies containing the type strain must be named Bacillus subtilis subsp. subtilis. Rule 40c The provisions of Rules 40a and 40b apply when a subspecies is divided into two or more subspecies, the original subspecies name being retained for that subspecies that contains the type strain. Note. Although the specific and subspecific epithets in the name of a type subspecies are the same, they do not contravene Rule 12b because they are based on the same type. Rule 40c The provisions of Rules 40a and 40b apply when a subspecies is divided into two or more subspecies, the original subspecies name being retained for that subspecies that contains the type strain. Note. Although the specific and subspecific epithets in the name of a type subspecies are the same, they do not contravene Rule 12b because they are based on the same type. Rule 40d The valid publication of a subspecific name that does not include the type of the species automatically creates the subspecies that includes the nomenclatural type of the species and whose name bears specific and subspecific epithets that are identical to the epithet of the name of the species, unless this subspecies is explicitly proposed in the same effective publication. Example: Publication of Bacillus subtilis subsp. spizizenii Nakamura et al. 1999 automatically created a new subspecies Bacillus subtilis subsp. subtilis. Rule 40d The valid publication of the name of a subspecies that does not include the type of the species, automatically creates the subspecies that includes the nomenclatural type of the species and whose name bears specific and subspecific epithets that are identical to the epithet of the name of the species, unless this subspecies is explicitly proposed in the same effective publication. 70 The author(s) of the species name must be cited as the author(s) of such an automatically created subspecific name. Example: Vibrio subtilis Ehrenberg to Bacillus subtilis Cohn 1872 comb. nov. to Bacillus subtilis subsp. subtilis Nakamura et al. 1999 subsp. nov. The correct authorship of the subspecies is Bacillus subtilis subsp. subtilis (Ehrenberg 1835) Nakamura et al. 1999 [Ehrenberg for the epithet and Nakamura for the new subspecies]. The authority of the species name must be cited as the authority, in parentheses, of the name of a subspecies that bears specific and subspecific epithets that are identical to the epithet of the name of the species. Note 1. A consequence of the valid publication of a subspecific name that does not include the type of the species is that another subspecies that includes the type and whose name bears the same specific and subspecific epithets as the name of the type must be validly published. Valid publication of the name at the rank of subspecies, which is based on the same type as that of the species and bears the same specific and subspecific epithets, must conform to Rules 27, 28b, 32a and 32b. Example: A consequence of the publication of Bacillus subtilis subsp. spizizenii Nakamura et al. 1999 is that the name of a new subspecies Bacillus subtilis subsp. subtilis must be validly published by the same authors that published the species name. This means that Nakamura et al. 1999 are automatically the authors of the name Bacillus subtilis subsp. subtilis (Ehrenberg 1835) Nakamura et al. 1999. The author(s) of the species name must be cited as the author(s) of such an automatically created subspecific name. Example: “Vibrio subtilis” Ehrenberg 1835 to Bacillus subtilis (Ehrenberg 1835) Cohn 1872 (Approved Lists 1980) comb. nov. to Bacillus subtilis subsp. subtilis subsp. nov. The correct authorship of the subspecies is Bacillus subtilis subsp. subtilis (Ehrenberg 1835) Nakamura et al. 1999 [Ehrenberg for the epithet and Nakamura et al. for the new subspecies]. The authority of the species name must be cited as the authority in parentheses of the name of a subspecies that bears specific and subspecific epithets that are identical to the epithet of the name of the species. Note 1. A consequence of the valid publication of a subspecific name that does not include the type of the species is that another subspecies that does include the type of the species and whose name bears the same specific and subspecific epithets as the name of the type must be validly published. Valid publication of the name at the rank of subspecies, which is based on the same type as that of the species and bears the same specific and subspecific epithets, must conform to Rules 28b and 32a. 71 Note 2. If names at the rank of subspecies that include the nomenclatural type of the species and whose name bears specific and subspecific epithets that are identical to the epithet of the name of the species, were not validly published as specified under Rule 40d Note 1, they may by action of the Judicial Commission be ruled to have been validly published as defined in Rule 46 of the 1975 and 1990 revisions of the International Code of Nomenclature of Bacteria and their authorships and dates of valid publication fixed accordingly. Note 2. If names at the rank of subspecies that include the nomenclatural type of the species and whose name bears specific and subspecific epithets that are identical to the epithet of the name of the species, were not validly published, as specified under Rule 40d Note 1, they may by action of the Judicial Commission be ruled to have been validly published, as defined in Rule 46 of the 1975 and 1990 revisions of the International Code of Nomenclature of Bacteria and their authorships and dates of valid publication fixed accordingly. Transfer of a Species to Another Genus Transfer of a Species to Another Genus Rule 41a When a species is transferred to another genus without any change of rank, the specific epithet must be retained, except for necessary changes of gender of adjectives used as specific epithets, to comply with Rule 12c(1), or it must be re-established if it has not been retained (in a previous publication), unless (see Rule 23a Note 1): Rule 41a When a species is transferred to another genus without any change of rank, the specific epithet must be retained, except for necessary changes of gender of adjectives used as specific epithets, to comply with Rule 12c(1), or it must be re-established if it has not been retained (in a previous publication). Examples: The epithet equigenitalis in the name Haemophilus equigenitalis Taylor et al. 1983 must not be changed on transfer to the genus Taylorella Sugimoto et al. 1984 as Taylorella equigenitalis (Taylor et al. 1983) Sugimoto et al. 1984. On transfer to the genus Rodentibacter Adhikary et al. 2017, the epithet pneumotropica in the name Pasteurella pneumotropica Jawetz 1950 (Approved Lists 1980) must be retained and adapted grammatically upon transfer to the genus Rodentibacter Adhikary et al. 2017 as Rodentibacter pneumotropicus (Jawetz 1950) Adhikary et al. 2017. However, the epithet must not be retained if (see Rule 23a Note 1): 72 (1) The resulting binary combination would be a later homonym. Example: Bernardet et al. [20] proposed Flavobacterium hydatis for Cytophaga aquatilis Strohl and Tait 1978 (Approved Lists 1980) on transfer to Flavobacterium because the name Flavobacterium aquatile already existed in that genus. (2) There is available an earlier validly published and legitimate specific or subspecific epithet. Example: not yet found. (1) The resulting binary combination would be a later homonym. Example: Bernardet et al. [17] proposed Flavobacterium hydatis for Cytophaga aquatilis Strohl and Tait 1978 (Approved Lists 1980) on transfer to Flavobacterium because the name Flavobacterium aquatile already existed in that genus. (2) There is available an earlier validly published and legitimate specific or subspecific epithet. An earlier validly published and legitimate specific or subspecific epithet is available for use. Example: Paenimyroides marinum (Song et al. 2013) Li 2024, rather than Paenimyroides aquimaris (Song et al. 2013) Zhang et al. 2023, must be proposed on transfer of Myroides aquimaris García-López et al. 2020 to Paenimyroides because there is an earlier validly published and legitimate specific epithet marinum in its basonym Flavobacterium marinum Song et al. 2013. Vreelandella halophila (Fendrich 1989) de la Haba et al. 2025, rather than Vreelandella utahensis (Sorokin and Tindall 2006) de la Haba et al. 2024, must be proposed on transfer of Halomonas utahensis Sorokin and Tindall 2006 to the genus Vreelandella de la Haba et al. 2024 because there is an earlier validly published and legitimate specific epithet halophila in its basonym Pseudomonas halophila Fendrich 1989. Rule 41b If the name of a genus is changed, the specific epithets of the species included under the original generic name must be retained for the same species, when they are transferred to the new genus, except for necessary Rule 41b If the name of a genus is changed, the specific epithets of the species included under the original generic name must be retained for the same species, when they are transferred to the new genus, except for necessary 73 changes of gender of adjectives used as specific epithets, to comply with Rule 12c(1). changes of gender of adjectives used as specific epithets, to comply with Rule 12c(1). Example: On transfer of the species Litoricola lipolytica Kim et al. 2007 to the genus Litorivicinus Deshmukh and Oren 2023, the new combination should be given as Litorivicinus lipolyticus (Kim et al. 2007) Deshmukh and Oren 2023 because the epithet must be retained except for the necessary grammatical adaption of its spelling from lipolytica to lipolyticus. Union of Taxa of Equal Rank Union of Taxa of Equal Rank Rule 42 In the case of subspecies, species, subgenera, and genera, if two or more of those taxa of the same rank are united, the oldest legitimate name or epithet is retained. Rule 42 In the case of subspecies, species, subgenera, and genera, if two or more of those taxa of the same rank are united, the earliest legitimate name or epithet is retained. Examples: When the genera Tabrizicola Tarhriz et al. 2014 and Xinfangfangia Hu et al. 2018 were united, the earlier name Tabrizicola was retained, and the new combination Tabrizicola soli (Hu et al. 2018) Ma et al. 2022 was proposed for Xinfangfangia soli Hu et al. 2018, the type species of Xinfangfangia. When uniting Corynebacterium mooreparkense Brennan et al. 2001 and C. variabile corrig. (Müller 1961) Collins 1987 as a single species within the genus Corynebacterium Lehmann and Neumann 1896 (Approved Lists 1980), Gelsomino et al. [18] treated C. mooreparkense as the later heterotypic synonym, thereby retaining the earlier epithet variabile. When uniting Marinobacter hydrocarbonoclasticus Gauthier et al. 1992 and Pseudomonas nautica Baumann et al. 1972 (Approved Lists 1980) as a single species within the genus Marinobacter Gauthier et al. 1992, the new combination 80 Example: If an author circumscribes a genus to include B acillus subtilis , the type species of the genus Bacillus, then the circumscribed genus must be named Bacillus. (2) If the author(s) did not adopt for a binary or ternary combination the earliest legitimate generic name, specific epithet, or subspecific epithet available for the taxon with its particular circumscription, position, and rank. Example: The name Bacillus whitmori Stanton and Fletcher 1921 was illegitimate as Whitmore had named the organism Bacillus pseudomallei in 1913 [26]. (3) If the specific epithet must be rejected under Rules 52 or 53. (4) If a new name or combination validly published before 31 December 2000 is a later homonym of a name of a taxon of prokaryotes, fungi, algae, protozoa or viruses. Example: Phytomonas Donovan 1909, a genus of flagellates, antedates Phytomonas Bergey et al. 1923, a genus of prokaryote (Opinion 14; Judicial Commission). (5) If a new name or combination validly published on or after 1 January 2001 is a later homonym of a validly published name of a taxon of prokaryotes or a name or combination validly published or available under the International Code of Nomenclature for algae, fungi, and plants or the International Code of Zoological Nomenclature. This does not affect validly Example: If an author circumscribes a genus to include Bacillus subtilis , the type species of the genus Bacillus, then the circumscribed genus must be named Bacillus. (2) If the author(s) did not adopt for a binary or ternary combination the earliest legitimate generic name, specific epithet, or subspecific epithet available for the taxon with its particular circumscription, position, and rank. Example: Vreelandella utahensis (Sorokin and Tindall 2006) de la Haba et al. 2024 is illegitimate because Vreelandella halophila should have been proposed instead by adopting the earliest legitimate epithet in the basonym Pseudomonas halophila Fendrich 1989. (3) If the specific epithet is illegitimate under Rules 52 or 53. (4) If a new name or combination validly published before or on 31 December 2000 is a later homonym of a name of a taxon of prokaryotes, fungi, algae, protozoa or viruses. Example: Catenococcus Sorokin 1994 is a later homonym of the algal generic name Catenococcus Hindák 1977 and therefore illegitimate. (5) If a new name or combination validly published on or after 1 January 2001 is a later homonym of a validly published name of a taxon of prokaryotes or a name or combination validly published or available under the International Code of Nomenclature for algae, fungi, and plants or the International Code of Zoological Nomenclature. This does not affect validly 81 published names or combinations not treated as later homonyms prior to 1 January 2001. published names or combinations not treated as later homonyms prior to 1 January 2001. Examples: Sphingobacterium composti Yoo et al. 2007 is illegitimate because it is a later homonym of Sphingobacterium composti Ten et al. 2007, which is validly published under this Code. Verticia Vandamme et al. 2015 is illegitimate because it is a later homonym of the insect generic name Verticia Malloch 1927, which is available under the International Code of Zoological Nomenclature. Brevinema Defosse et al. 1995 is a later homonym of the nematode genus name Brevinema Stegarescu 1980, but it is not considered illegitimate for this reason as it was validly published before 2001. (6) If the nomenclatural type of the taxon to which the name was applied is a taxon with an illegitimate name itself (see Rules 20a, 21a and 51a). Example: The name Yaniaceae Li et al. 2005 is illegitimate because the name of the type genus Yania Li et al 2004 is illegitimate. (7) If an inaccurate ending was chosen for the name of a taxon above genus rank. Examples: Kiritimatiellae Spring et al. 2017, illegitimate class name (Opinion 116); Longimicrobia (sic) Pascual et al. 2016, legitimate class name but to be corrected to Longimicrobiia corrig. Pascual et al. 2016 (Opinion 116); Methanobacteria Boone 2002, legitimate and accurately spelled class name (Opinion 128). Illegitimate Epithets Illegitimate Epithets 82 Rule 52 The following are not to be regarded as specific or subspecific epithets: (1) A word or phrase that is not intended as a specific epithet. Example: Bacillus nova species Matzuschita. (2) A word that is an ordinal adjective higher than ten used for enumeration. Example: undecimus, duodecimus etc. (3) A number or letter. Example: α in Bacillus α von Freudenreich. Rule 52 The following are not to be regarded as specific or subspecific epithets: (1) A word or phrase that is not intended as a specific epithet. Example: Bacillus nova species Matzuschita. (2) A word that is an ordinal adjective higher than ten used for enumeration. Example: undecimus, duodecimus etc. (3) A number or letter. Example: α in Bacillus α von Freudenreich. Rule 53 An epithet is illegitimate if it duplicates a specific or subspecific epithet previously validly published for a species or subspecies of the same genus and if this species or subspecies is a different bacterium with a name based upon another type. Example: Bacillus pallidus Scholz et al. 1988 is based on the nomenclatural type, strain H12; the specific epithet pallidus cannot be used for Bacillus pallidus Zhou et al. 2008, which is a different bacterium with a name based upon another type. Rule 53 An epithet is illegitimate if it duplicates a specific or subspecific epithet previously validly published for a species or subspecies of the same genus and if this species or subspecies is a different bacterium with a name based upon another type. Example: Bacillus pallidus Scholz et al. 1988 is based on the nomenclatural type, strain H12; the specific epithet pallidus cannot be used for Bacillus pallidus Zhou et al. 2008, which is a different bacterium with a name based upon another type. Replacement of Names Replacement of Names or Epithets 83 Rule 54 A name or epithet illegitimate according to Rules 51b, 53 or 56a is replaced by the oldest legitimate name or epithet in a binary or ternary combination that in the new position will be in accordance with the Rules. If no legitimate name or epithet exists, one must be designated. A specific epithet is not rendered illegitimate by publication of a species name in which the generic name is illegitimate (Rule 32b). Authors may use such an epithet, provided that there is no obstacle to its employment in the new position or sense; the resultant combination is treated as a new name and is to be ascribed to the author(s) of the combination. However, the epithet is ascribed to the original author(s). Example: Pfeifferella pseudomallei (Whitmore 1913) Ford 1928 is an illegitimate combination since Pfeifferella is a homonym of a protozoan generic name (Opinion 14; Judicial Commission [27]). The epithet pseudomallei can be used for this organism in another genus, Pseudomonas pseudomallei (Whitmore 1913) Haynes 1957. Rule 54 A name or epithet illegitimate according to Rules 51b, 53 or 56a is replaced by the earliest legitimate name or epithet in a binary or ternary combination that in the new position will be in accordance with the Rules (but see Rule 56b). If no legitimate name or epithet exists, one must be proposed. A specific epithet is not rendered illegitimate by publication of a species name in which the generic name is illegitimate (Rule 32b). An author may use such an epithet, provided that there is no obstacle to its employment in the new position or sense; the resultant combination is treated as a new name and is ascribed to the author(s) of the combination. However, the epithet is ascribed to the original author(s). Rule 55 A validly published name or epithet may not be replaced merely because of the following: (1) It is inappropriate. Example: Bacteroides melaninogenicus does not produce melanin (see Schwabacher et al. [28]). Rule 55 A validly published name or epithet is not illegitimate, and may not be replaced, merely because of the following: (1) It is inappropriate. Example: Bacteroides melaninogenicus (Oliver and Wherry 1921) Roy and Kelly 1939 (Approved Lists 1980) does not produce melanin (see Schwabacher et al. [23]). 84 (2) It is disagreeable. ( 3) Another name is preferable. (4) Another name is better known. Example: Corynebacterium pseudodiphtheriticum cannot be rejected because the synonym Corynebacterium hofmannii is better known. (5) It no longer describes the organism. Example: Haemophilus influenzae (does not cause influenza). (6) It has been cited incorrectly; an incorrect citation can be rectified by a later author. Example: Proteus morganii Yale 1939 (see Lessel [29]). (2) It is disagreeable. Example: Myxococcus llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogochensis Chambers et al. 2021. (3) Another name or epithet is preferable. (4) Another name or epithet is better known. (5) It no longer describes the organism. Example: Haemophilus influenzae corrig. (Lehmann and Neumann 1896) Winslow et al. 1917 (Approved Lists 1980) (does not cause influenza). (6) It has been cited incorrectly; an incorrect citation can be rectified by a later author. Example: Proteus morganii Yale 1939 (see Lessel [24]). (7) It contains a grammatical or orthographic error. See Section 9 for spelling corrections. Rejection of Names Rejection of Names or Epithets Rule 56a Rule 56a 85 Only the Judicial Commission can place names on the list of rejected names (nomina rejicienda) (see Rule 23a, Note 4, and Appendix 4). A name may be placed on this list for various reasons, including the following: (1) An ambiguous name (nomen ambiguum), i.e., a name which has been used with different meanings and, thus, has become a source of error. Example: Aerobacter Beijerinck 1900 (Opinion 46; Judicial Commission). (2) A doubtful name (nomen dubium), i.e., a name whose application is uncertain. Example: Leuconostoc citrovorum (Opinion 45; Judicial Commission). ( 3) A name causing confusion (nomen confusum), i.e., a name based upon a mixed culture. Example: Malleomyces Hallier 1870. (4) A perplexing name (nomen perplexum), a name whose application is known but causes uncertainty in prokaryotic nomenclature (see Rule 57c). Example: Bacillus limnophilus Bredemann and Stürck in Stürck 1935 (Greek– Greek, marsh loving) and Bacillus limophilus Migula 1900 (Latin–Greek, mud loving); see Index Bergeyana, p. 196 [30]. Only the Judicial Commission can place names and epithets on the list of rejected names (nomina rejicienda) (see Rule 23a, Note 4, and Appendix 4). A name or epithet may be placed on this list for various reasons, including the following: (1) An ambiguous name (nomen ambiguum), i.e., a name that has been used with different meanings and thus has become a source of error. Examples: Aerobacter Beijerinck 1900 (Opinion 46); Aeromonas punctata (Zimmermann 1890) Snieszko 1957 (Approved Lists 1980) (Opinion 123). (2) A doubtful name (nomen dubium), i.e., a name whose application is uncertain. Example: Leuconostoc citrovorum (Opinion 45; Judicial Commission). (3) A name causing confusion (nomen confusum), i.e., a name based upon a mixed culture. Example: Malleomyces Hallier 1870. Thermomicrobium fosteri Phillips and Perry 1976 (Approved Lists 1980) (Opinion 107). (4) A perplexing name (nomen perplexum), a name whose application is known but causes uncertainty in prokaryotic nomenclature because of a similarity in spelling (see Rule 57c). Example: Mycobacterium marianum (Opinion 53; Judicial Commission). 86 (5) A perilous name (nomen periculosum), i.e., a name that the application is likely to lead to accidents endangering health or life or of serious economic consequences. Example: Yersinia pseudotuberculosis subsp. pestis (Opinion 60; Judicial Commission) is to be rejected as a nomen periculosum. Note 1. This application is restricted to a proposed change in the specific epithet of a species that is widely recognized as contagious, virulent, or highly toxigenic, for example, to that of a subspecies of a species having a different host range or a degree of contagiousness or virulence. If the Judicial Commission recognizes a high order of risk to health, or of serious economic consequences, an Opinion may be issued that the taxon be maintained as a separate species, without prejudice to the recognition or acceptance of its genetic relatedness to another taxon. (5) A perilous name (nomen periculosum), i.e., a particular kind (see Note 1) of name whose application is likely to lead to accidents endangering health or life or of serious economic consequences. Example: Yersinia pseudotuberculosis subsp. pestis (Lehmann and Neumann 1896) Bercovier et al. 1981 was rejected as a nomen periculosum in order to maintain Yersinia pestis (Lehmann and Neumann 1896) van Loghem 1944 (Approved Lists 1980) and Yersinia pseudotuberculosis (Pfeiffer 1889) Smith and Thal 1965 (Approved Lists 1980) as separate species (Opinion 60; Judicial Commission). Note 1. This application is restricted to a proposed change in the specific epithet of a species that is widely recognized as contagious, virulent, or highly toxigenic, for example, to that of a subspecies of a species having a different host range or a degree of contagiousness or virulence. If the Judicial Commission recognizes a high order of risk to health, or of serious economic consequences, an Opinion may be issued that the taxon be maintained as a separate species, without prejudice to the recognition or acceptance of its genetic relatedness to another taxon. Note 2. Rejecting an epithet within a name automatically places that epithet in all of the name's homotypic synonyms on the list of rejected epithets (Opinion 106), except for the synonyms in which that epithet is conserved (Opinion 60). Note 3. Adding a name to the list of rejected names does not imply that names with the same spelling but a different category are also on that list. 87 Example: The placement of the class name Bacteria Haeckel 1894 (Approved Lists 1980) on the list of rejected names does not imply the simultaneous rejection of the domain name Bacteria Woese et al. 2024 (Opinion 128). Conservation of Names Conservation of Names or Epithets Rule 56b A conserved name (nomen conservandum) is a name that must be used instead of all earlier synonyms and homonyms. Note 1. A conserved name (nomen conservandum) is conserved against all other names for the taxon, whether these are cited in the corresponding list of rejected names or not, so long as the taxon concerned is not united with another taxon bearing a legitimate name. In the event of union or reunion with another taxon, the earlier of the two competing names is adopted in accordance with Rules 23a and 23b. Note 2. Only the Judicial Commission can place names on the list of conserved names (nomina conservanda) (see also Rule 23a, Note 4, and Appendix 4). Rule 56b A conserved name (nomen conservandum) is a name that must be used instead of all earlier synonyms and homonyms. Similarly, a conserved epithet must be used instead of all earlier counterparts. Example: Rhodococcus Zopf 1891 (Approved Lists 1980) was conserved over Rhodococcus Hansgirg 1884 in Opinion 130. Note 1. A conserved name (nomen conservandum) is conserved against all other names for the taxon, whether these are cited in the corresponding list of rejected names or not, so long as the taxon concerned is not united with another taxon bearing a legitimate name. In the event of union or reunion with another taxon, the earlier of the two competing names is adopted in accordance with Rules 23a and 23b. Note 2. Only the Judicial Commission can place names and epithets on the list of conserved names (nomina conservanda) (see also Rule 23a, Note 4, and Appendix 4). Note 3. Conserving an epithet within a name automatically places that epithet in all of the name's homotypic synonyms on the list of conserved 88 epithets (Opinion 106), except for the synonyms in which that epithet is rejected (Opinion 60). Note 4. For information on conserving a name for the purpose of changing its nomenclatural type, see Rule 37a(2) instead. Section 9. Orthography Section 9. Orthography Rule 57a Any name or epithet should be written in conformity with the spelling of the word from which it is derived and in strict accordance with the rules of Latin and Latinization. Exceptions are provided for typographic and orthographic errors in Rule 61 and orthographic variants in Rules 62a and 62b (see also Appendix 9). Rule 57a Any name or epithet must be written in conformity with the spelling of the word from which it is derived and in strict accordance with the rules of Latin and Latinization. Exceptions are provided for typographic and orthographic errors in Rule 61 and orthographic variants in Rules 62a and 62b (see also Appendix 9). Note. Names of cyanobacterial taxa that are considered validly published under the International Code of Nomenclature of Prokaryotes because they are validly published under the International Code of Nomenclature for algae, fungi, and plants (see Rule 30) are spelled in accordance with the provisions of the latter Code (but see Section 3). Rule 57b In this Code, orthographic variant means a name (or epithet) that differs from another name only in the transliteration into Latin of the same word from a language other than Latin or in its grammatical correctness. Example: Haemophilus, Hemophilus. Rule 57b In this Code, an orthographic variant means a name (or epithet) that differs from another name only in transliteration into Latin of the same word from a language other than Latin that does not use the Latin alphabet or in its grammatical correctness. 89 Example: Haemophilus , Hemophilus ; Xanthocytophaga flava , Xanthocytophaga flavus Rule 57c If two or more generic names or two or more epithets in the same genus are so similar (although the words are from different sources) as to cause uncertainty, they may be treated as perplexing names (nomina perplexa) and the matter referred to the Judicial Commission [see Rule 56a(4)]. Note 1. Orthographic variants may be corrected by any author, provided this is done in accordance with the Note to Rule 61. Note 2. Perplexing names may be placed on the list of rejected names only by the Judicial Commission, because decisions on the status of names derived from different sources differing in one or more letters affect many wellknown names in the nomenclature of prokaryotes. Examples: Salmonella gamaba and Salmonella gambaga. Rule 57c If two or more names or two or more epithets in the same genus are so similar (although the words are from different sources) as to cause uncertainty, they may be treated as perplexing names (nomina perplexa) and the matter referred to the Judicial Commission [see Rule 56a(4)]. Note 1. Orthographic variants may be corrected by any author, provided this is done in accordance with the Note to Rule 61. Note 2. Perplexing names may be placed on the list of rejected names only by the Judicial Commission, because decisions on the status of names derived from different sources differing in one or more letters affect many well-known names in the nomenclature of prokaryotes. Example: The name Mycobacterium marianum Penso 1953 is placed on the list of nomina rejicienda as a nomen perplexum because it is a source of confusion for resembling the name Mycobacterium marinum Aronson 1926 (Approved Lists 1980). Rule 58 If doubt exists about different spellings of the same name or epithet, or if two spellings are sufficiently alike so as to be confused, the question should be referred to the Judicial Commission, which may issue an Opinion. If one of the spellings is preferred by the Judicial Commission, that spelling should be used by succeeding authors. Rule 58 If doubt exists about different spellings of the same name or epithet, or if two spellings are sufficiently alike so as to be confused, the question should be referred to the Judicial Commission, which may issue an Opinion. If one of the spellings is preferred by the Judicial Commission, that spelling must be used by succeeding authors. 96 (4) A pro - validly published and pro - legitimate Candidatus name cannot compete with a validly published and legitimate name for priority (Rule 23a), but it can compete with another pro-validly published and pro-legitimate Candidatus name for pro-priority (Rule 71), by analogy with Rule 23a. (5) If a nomenclatural question arises in connection with a Candidatus name which is not expressly dealt with in Section 10, the solution to be chosen is in accordance with the Rules and has the most obvious analogy to a nomenclatural solution provided for in other Sections of this Code. Doubtful cases should be referred to the Judicial Commission (Appendix 8). The replacement of a pro-illegitimate name or epithet is conducted by analogy with Rules 54-55, but see also Rule 72(4)(b). Note. For the history of the Candidatus status see Appendix 11. Section 10 supersedes Appendix 11 in the event of a conflict. (4) A pro - validly published and pro - legitimate Candidatus name cannot compete with a validly published and legitimate name for priority (Rule 23a), but it can compete with another pro-validly published and prolegitimate Candidatus name for pro-priority (Rule 71), by analogy with Rule 23a. (5) If a nomenclatural question arises in connection with a Candidatus name which is not expressly dealt with in Section 10, the solution to be chosen is in accordance with the Rules and has the most obvious analogy to a nomenclatural solution provided for in other Sections of this Code. Doubtful cases should be referred to the Judicial Commission (Appendix 8). The replacement of a pro-illegitimate name or epithet is conducted by analogy with Rules 54-55, but see also Rule 72(4)(b). Note. For the history of the Candidatus status see Appendix 11. Section 10 supersedes Appendix 11 in the event of a conflict. Pro - valid publication of a Candidatus name Pro - valid publication of a Candidatus name Rul e 67 A Candidatus name for a new taxon, or a new combination or nomen novum for an existing Candidatus taxon, is not pro-validly published, unless the following criteria are met: (1) The name meets the requirements for publication in Rule 27(1). Rule 67 A Candidatus name for a new taxon, or a new combination or nomen novum for an existing Candidatus taxon, is not pro-validly published, unless the following criteria are met: (1) The name meets the requirements for publication in Rule 27(1). 97 (2) The name meets the requirements for the formation of Candidatus names in Rule 66(1) in conjunction with the requirements for taxon descriptions in Rule 27(2). (3) The name meets the requirements for nomenclatural types in Rule 27(3), except for the following: (a) In the case of the name of a species or subspecies, the name does not meet the requirements of Rule 30 but meets the requirements of Rule 69. (b) In the case of the name of a taxon above the rank of species, the name of its nomenclatural type is not validly published, but it is pro-validly published and pro-legitimate. Note. Possible exceptions to Rule 67 are defined in Rule 68(2), Rule 68(3) and Rule 68(4). (2) The name meets the requirements for the formation of Candidatus names in Rule 66(1) in conjunction with the requirements for taxon descriptions in Rule 27(2). (3) The name meets the requirements for nomenclatural types in Rule 27(3), except for the following: (a) In the case of the name of a species or subspecies, the name does not meet the requirements of Rule 30 but meets the requirements of Rule 69. (b) In the case of the name of a taxon above the rank of species, the name of its nomenclatural type is not validly published, but it is pro-validly published and pro-legitimate. Note. Possible exceptions to Rule 67 are defined in Rule 68(2), Rule 68(3) and Rule 68(4). Rule 68 The date of pro-valid publication of a Candidatus name is the date of its publication in the IJSEM. (1) If the original proposal of the new Candidatus name or new Candidatus combination was not published in the IJSEM, pro-valid publication of the name may be achieved by its announcement in an IJSEM Candidatus List, by analogy with the announcement of a name in a Validation List for the purpose of its valid publication (Rule 27 Note 1). Rule 68 The date of pro-valid publication of a Candidatus name is the date of its publication in the IJSEM. (1) If the original proposal of the new Candidatus name or new Candidatus combination was not published in the IJSEM, pro-valid publication of the name may be achieved by its announcement in an IJSEM Candidatus List, by analogy with the announcement of a name in a Validation List for the purpose of its valid publication (Rule 27 Note 1). 98 (2) If a Candidatus name does not meet the requirements of Rule 67, but has been included in an IJSEM Candidatus List that was published before 1 January 2025, the name is pro-validly published. (a) If the nomenclatural type of such a name was not mentioned in the Candidatus List, a nomenclatural type will be provided in an addendum to the respective Candidatus List, published separately in the IJSEM by the List Editors. Such an addendum does not affect the date of pro-valid publication. If several possible nomenclatural types in accordance with Rule 67(3) have been provided in the effective publication, one shall be selected. (b) If a nomenclatural type in accordance with Rule 67(3) cannot be determined for a name that is pro-validly published because of its inclusion in a Candidatus List, this shall also be announced in an addendum to a Candidatus List, and the name considered pro-illegitimate. (3) If a name meets the requirements given in Rule 67, with the exception of the use of the word “Candidatus” as stipulated by Rule 67(2), and the name is included in an IJSEM Candidatus List, then the name is pro-validly published and is considered to be a Candidatus name. (4) When a name that has been considered validly published is found to not meet the requirements for nomenclatural types in Rule 27(3), but is found to meet the requirements of Rule 67(3), the name should be given Candidatus status by announcement in an IJSEM Candidatus List, stating the reasons for not meeting the requirements of Rule 27(3) and including the information required by Rule 67(3). The presumed date of valid publication of the name shall then become its date of pro-valid publication. (2) If a Candidatus name does not meet the requirements of Rule 67 , but has been included in an IJSEM Candidatus List that was published before 1 January 2025, the name is pro-validly published. (a) If the nomenclatural type of such a name was not mentioned in the Candidatus List, a nomenclatural type will be provided in an addendum to the respective Candidatus List, published separately in the IJSEM by the List Editors. Such an addendum does not affect the date of pro-valid publication. If several possible nomenclatural types in accordance with Rule 67(3) have been provided in the effective publication, one shall be selected. (b) If a nomenclatural type in accordance with Rule 67(3) cannot be determined for a name that is pro-validly published because of its inclusion in a Candidatus List, this shall also be announced in an addendum to a Candidatus List, and the name considered pro-illegitimate. (3) If a name meets the requirements given in Rule 67, with the exception of the use of the word “Candidatus” as stipulated by Rule 67(2), and the name is included in an IJSEM Candidatus List, then the name is pro-validly published and is considered to be a Candidatus name. (4) When a name that has been considered validly published is found to not meet the requirements for nomenclatural types in Rule 27(3), but is found to meet the requirements of Rule 67(3), the name should be given Candidatus status by announcement in an IJSEM Candidatus List, stating the reasons for not meeting the requirements of Rule 27(3) and including the information required by Rule 67(3). The presumed date of valid publication of the name shall then become its date of pro-valid publication. 99 (5) A Candidatus name that has previously been pro-validly published in the IJSEM may be included in an IJSEM Candidatus List for the sole purpose of its orthographic or grammatical correction (Section 9). Such inclusion shall not affect the date of pro-valid publication. Note. In order to determine the relative pro-priority of Candidatus names that were included in the same Candidatus List for the purpose of their provalid publication, each included name should be assigned a number reflecting the date of receipt of the request for inclusion in the Candidatus List, by analogy with Rule 24b(4). Within a Candidatus List which does not contain such numbers, relative pro-priority of each name is determined by the date of its original publication as indicated in the Candidatus List. Candidatus Lists published prior to 1 January 2025 may indicate more than one original publication per name. If so, the relative pro-priority of a name is determined by the date of the earliest indicated original publication of that name. (5) A Candidatus name that has previously been pro-validly published in the IJSEM may be included in an IJSEM Candidatus List for the sole purpose of its orthographic or grammatical correction (Section 9). Such inclusion shall not affect the date of pro-valid publication. Note. In order to determine the relative pro-priority of Candidatus names that were included in the same Candidatus List for the purpose of their pro-valid publication, each included name should be assigned a number reflecting the date of receipt of the request for inclusion in the Candidatus List, by analogy with Rule 24b(4). Within a Candidatus List which does not contain such numbers, relative pro-priority of each name is determined by the date of its original publication as indicated in the Candidatus List. Candidatus Lists published prior to 1 January 2025 may indicate more than one original publication per name. If so, the relative pro-priority of a name is determined by the date of the earliest indicated original publication of that name. Nomenclatural type of a Candidatus name Nomenclatural type of a Candidatus name Rule 69 The nomenclatural type of a pro-validly published Candidatus name is regulated by analogy with Section 4, except for the following: (1) The kind of nomenclatural type of a pro-validly published Candidatus name at the rank of species or subspecies is one of the following (in order of decreasing preference for the kind of nomenclatural type): Rule 69 The nomenclatural type of a pro-validly published Candidatus name is regulated by analogy with Section 4, except for the following: (1) The kind of nomenclatural type of a pro-validly published Candidatus name at the rank of species or subspecies is one of the following (in order of decreasing preference for the kind of nomenclatural type): 100 (a) A culture containing living cells of the species or subspecies from which characters of use in taxonomy can be obtained, but which does not meet the requirements of Rule 30. (b) A preserved specimen containing cells of the species or subspecies from which characters of use in taxonomy can be obtained. (c) A genome sequence obtained from the species or subspecies and deposited in one of the databases belonging to the International Nucleotide Sequence Database Collaboration (INSDC). (d) A gene sequence obtained from the species or subspecies and deposited in one of the databases belonging to the INSDC. (2) For the purpose of designating a nomenclatural type under Rule 69(1)(a) or Rule 69(1)(b), the culture or preserved specimen must be deposited in an appropriate collection. Evidence of its availability from that collection must be provided at the time of publication in the IJSEM. (3) For the purpose of designating a nomenclatural type according to Rule 69(1)(c) or according to Rule 69(1)(d), its INSDC nucleotide sequence accession numbers must be provided at the time of publication in the IJSEM, i.e., identifiers that can be used directly to obtain a nucleotide sequence from INSDC, without the need for an intermediate identifier. The INSDC nucleotide sequence accession numbers provided must specifically and completely cover the nucleotide sequence, and all associated sequence data must be available at the time of publication in the IJSEM. All sequence identifiers required to specifically and completely cover the sequence must be cited in the effective publication. (a) A culture containing living cells of the species or subspecies from which characters of use in taxonomy can be obtained, but which does not meet the requirements of Rule 30. (b) A preserved specimen containing cells of the species or subspecies from which characters of use in taxonomy can be obtained. (c) A genome sequence obtained from the species or subspecies and deposited in one of the databases belonging to the International Nucleotide Sequence Database Collaboration (INSDC). (d) A gene sequence obtained from the species or subspecies and deposited in one of the databases belonging to the INSDC. (2) For the purpose of designating a nomenclatural type under Rule 69(1)(a) or Rule 69(1)(b), the culture or preserved specimen must be deposited in an appropriate collection. Evidence of its availability from that collection must be provided at the time of publication in the IJSEM. (3) For the purpose of designating a nomenclatural type according to Rule 69(1)(c) or according to Rule 69(1)(d), its INSDC nucleotide sequence accession numbers must be provided at the time of publication in the IJSEM, i.e., identifiers that can be used directly to obtain a nucleotide sequence from INSDC, without the need for an intermediate identifier. The INSDC nucleotide sequence accession numbers provided must specifically and completely cover the nucleotide sequence, and all associated sequence data must be available at the time of publication in the IJSEM. All sequence identifiers required to specifically and completely cover the sequence must be cited in the effective publication. 101 (a) If sequence identifiers other than INSDC nucleotide sequence accession numbers have been cited in the effective publication, INSDC nucleotide sequence accession numbers that can be unambiguously mapped to those identifiers must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. (b) If INSDC nucleotide sequence accession numbers have been cited in the effective publication but not in the protologue (see Rule 27), these INSDC nucleotide sequence accession numbers must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. (4) For the purpose of designating a nomenclatural type under Rule 69(1)(d), the protologue must include a statement indicating that, in the taxonomic opinion of the authors, the gene sequence is sufficiently specific to distinguish the taxon from other taxa of the same rank. If such a statement has not been included in the protologue (see Rule 27), the statement must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. Note. Possible exceptions to Rule 69(2), Rule 69(3) and Rule 69(4) are defined in Rule 68(2). The nomenclatural type should conform to minimal standards, when these are available for the respective kind of nomenclatural type at the time of effective publication. (a) If sequence identifiers other than INSDC nucleotide sequence accession numbers have been cited in the effective publication, INSDC nucleotide sequence accession numbers that can be unambiguously mapped to those identifiers must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. (b) If INSDC nucleotide sequence accession numbers have been cited in the effective publication but not in the protologue (see Rule 27), these INSDC nucleotide sequence accession numbers must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. (4) For the purpose of designating a nomenclatural type under Rule 69(1)(d), the protologue must include a statement indicating that, in the taxonomic opinion of the authors, the gene sequence is sufficiently specific to distinguish the taxon from other taxa of the same rank. If such a statement has not been included in the protologue (see Rule 27), the statement must be provided when requesting the inclusion of the taxon name in an IJSEM Candidatus List. Note. Possible exceptions to Rule 69(2), Rule 69(3) and Rule 69(4) are defined in Rule 68(2). The nomenclatural type should conform to minimal standards, when these are available for the respective kind of nomenclatural type at the time of effective publication. Rule 70 The nomenclatural type of a pro-validly published Candidatus name at the rank of species or subspecies may be replaced by another nomenclatural type, provided that the replacement type meets the requirements of Rule 69. Such a proposed replacement must be published in the IJSEM. Rule 70 The nomenclatural type of a pro-validly published Candidatus name at the rank of species or subspecies may be replaced by another nomenclatural type, provided that the replacement type meets the requirements of Rule 69. Such a proposed replacement must be published in the IJSEM. 102 (1) The possible reasons for replacing the nomenclatural type of a Candidatus species or subspecies are the following: (a) The nomenclatural type is no longer available. This includes deposits of living cultures or specimens that are no longer available, and sequence records that have been suppressed by INSDC. (b) The kind of the proposed replacement type is preferred over the kind of the nomenclatural type as indicated in Rule 69(1). (c) The proposed replacement type is of the same the kind as the designated nomenclatural type, but the proposed replacement type is of higher quality. (2) The proposal of a replacement type in the IJSEM must state the reason for the replacement in sufficient detail. The proposal must also provide evidence that the replacement type belongs to the species or subspecies according to the taxonomic view expressed in the effective publication of the name of the species or subspecies. (3) The proposal of a replacement type is void if it does not meet the requirements set out in this Rule. Doubtful cases should be referred to the Judicial Commission (Appendix 8). Note. A replacement type must not be proposed if it meets the requirements of Rule 30. If it does, it should be used instead to propose the name of the species or subspecies for valid publication, provided that this can be done in accordance with Section 5 and Rule 72 of this Code. (1) The possible reasons for replacing the nomenclatural type of a Candidatus species or subspecies are the following: (a) The nomenclatural type is no longer available. This includes deposits of living cultures or specimens that are no longer available, and sequence records that have been suppressed by INSDC. (b) The kind of the proposed replacement type is preferred over the kind of the nomenclatural type as indicated in Rule 69(1). (c) The proposed replacement type is of the same the kind as the designated nomenclatural type, but the proposed replacement type is of higher quality. (2) The proposal of a replacement type in the IJSEM must state the reason for the replacement in sufficient detail. The proposal must also provide evidence that the replacement type belongs to the species or subspecies according to the taxonomic view expressed in the effective publication of the name of the species or subspecies. (3) The proposal of a replacement type is void if it does not meet the requirements set out in this Rule. Doubtful cases should be referred to the Judicial Commission (Appendix 8). Note. A replacement type must not be proposed if it meets the requirements of Rule 30. If it does, it should be used instead to propose the name of the species or subspecies for valid publication, provided that this can be done in accordance with Section 5 and Rule 72 of this Code. 103 Candidatus names with nomenclatural pro - standing Candidatus names with nomenclatural pro - standing Rule 71 If a taxon with a given circumscription, position, and rank has no correct name (Rule 23a), the taxon can bear only one pro-correct name, i.e., the pro-validly published and pro-legitimate name with the earliest date of provalid publication (Rule 68). Exceptions to pro-priority can be made by conservation or rejection. (1) A pro-validly published name or epithet cannot be conserved over a validly published name or epithet, but a pro-validly published name or epithet may be conserved by the Judicial Commission over another provalidly published name or epithet by analogy with Rule 56b. (2) The Judicial Commission may, by analogy with Rule 56a, place a provalidly published name or epithet on the list of rejected names or epithets. Such rejection equally applies to validly published names or epithets. Note. A taxon for which there is neither a validly published and legitimate name, nor a pro-validly published and pro-legitimate name, has neither a correct name nor a pro-correct name. Rule 71 If a taxon with a given circumscription, position, and rank has no correct name (Rule 23a), the taxon can bear only one pro-correct name, i.e., the pro-validly published and pro-legitimate name with the earliest date of pro-valid publication (Rule 68). Exceptions to pro-priority can be made by conservation or rejection. (1) A pro-validly published name or epithet cannot be conserved over a validly published name or epithet, but a pro-validly published name or epithet may be conserved by the Judicial Commission over another provalidly published name or epithet by analogy with Rule 56b. (2) The Judicial Commission may, by analogy with Rule 56a, place a provalidly published name or epithet on the list of rejected names or epithets. Such rejection equally applies to validly published names or epithets. Note. A taxon for which there is neither a validly published and legitimate name, nor a pro-validly published and pro-legitimate name, has neither a correct name nor a pro-correct name. Rule 72 From 1 January 2025, when proposing a taxon name for the purpose of its valid publication under this Code (Rule 27), a pro-validly published and prolegitimate Candidatus name, or epithet thereof, must be reused under certain conditions, depending on the taxonomic view expressed by the authors in the effective publication (Rules 25a, 25b) containing the proposal. Rule 72 From 1 January 2025, when proposing a taxon name for the purpose of its valid publication under this Code (Rule 27), a pro-validly published and prolegitimate Candidatus name, or epithet thereof, must be reused under certain conditions, depending on the taxonomic view expressed by the authors in the effective publication (Rules 25a, 25b) containing the 104 Under all other conditions, a pro - validly published and pro - legitimate Candidatus name, or epithet thereof, must not be reused. This Rule is not retroactive. (1) If a name above the rank of species is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name of the same rank, then that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (2) If a name at the rank of species or subspecies is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name at the same rank and in the same position, then that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (3) If a name at the rank of species or subspecies is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name at the rank of species or subspecies and in a different position, then the final epithet of that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (4) Not to reuse a pro-validly published and pro-legitimate Candidatus name above genus rank when proposing a name for valid publication, while considering the two names to be synonymous, is permitted where this is a necessary condition to form a name, according to the Rules of this Code. proposal. Under all other conditions, a pro - validly published and pro - legitimate Candidatus name, or epithet thereof, must not be reused. This Rule is not retroactive. (1) If a name above the rank of species is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name of the same rank, then that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (2) If a name at the rank of species or subspecies is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name at the same rank and in the same position, then that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (3) If a name at the rank of species or subspecies is proposed for the purpose of its valid publication under this Code, and if, in the taxonomic opinion of the authors, the proposed name is a synonym of a pro-validly published and pro-legitimate Candidatus name at the rank of species or subspecies and in a different position, then the final epithet of that Candidatus name must be reused, unless to do so would contravene a Rule of this Code. (4) Not to reuse a pro-validly published and pro-legitimate Candidatus name above genus rank when proposing a name for valid publication, while considering the two names to be synonymous, is permitted where 105 Example. If the hypothetical genus with the pro-validly published and prolegitimate name “Candidatus Dedyshiibacter” was the nomenclatural type of a family with the pro-validly published and pro-legitimate name, “Candidatus Dedyshiibacteraceae”, and if authors intended to validly publish the name of another genus in the same family, e.g., Dedyshiibacteroides, as well as the name of the family, but cannot propose the name Dedyshiibacter for valid publication, at the time, then they may propose the name Dedyshiibacteroidaceae for the family, but not Dedyshiibacteraceae. In this case, the authors should immediately list “Candidatus Dedyshiibacteraceae” as a synonym of Dedyshiibacteroidaceae. this is a necessary condition to form a name, acc ording to the Rules of this Code. Example. If the hypothetical genus with the pro-validly published and prolegitimate name “Candidatus Dedyshiibacter” was the nomenclatural type of a family with the pro-validly published and pro-legitimate name, “Candidatus Dedyshiibacteraceae”, and if authors intended to validly publish the name of another genus in the same family, e.g., Dedyshiibacteroides, as well as the name of the family, but cannot propose the name Dedyshiibacter for valid publication, at the time, then they may propose the name Dedyshiibacteroidaceae for the family, but not Dedyshiibacteraceae. In this case, the authors should immediately list “Candidatus Dedyshiibacteraceae” as a synonym of Dedyshiibacteroidaceae. Rule 73 The original authors of a Candidatus name or epithet reused under Rule 72, whether or not as a synonym, are cited by giving the name of the taxon, followed in parentheses by the word “ex” and the name of the original authors and the year of pro-valid publication (see Rule 14b and Rule 33c Note 2). Wherein other authors are subsequently to be cited in parentheses (Rule 34b), this form of citation is retained by analogy with the perpetuation of “ex” in Rule 33c Note 2. Rule 73 is retroactive, but failure to comply with it does not alter the nomenclatural status of a name. Note. The original Candidatus name from which a reused epithet is taken is known as the pro-basonym, not the basonym (Rule 34a). Rule 73 The original authors of a Candidatus name or epithet reused under Rule 72, whether or not as a synonym, are cited by giving the name of the taxon, followed in parentheses by the word “ex” and the name of the original authors and the year of pro-valid publication (see Rule 14b and Rule 33c Note 2). Wherein other authors are subsequently to be cited in parentheses (Rule 34b), this form of citation is retained by analogy with the perpetuation of “ex” in Rule 33c Note 2. Rule 73 is retroactive, but failure to comply with it does not alter the nomenclatural status of a name. Note. The original Candidatus name from which a reused epithet is taken is known as the pro-basonym, not the basonym (Rule 34a). CHAPTER 4. ADVISORY NOTES CHAPTER 4. ADVISORY NOTES 112 was jointly prepared by the IAVS and the Fédération Internationale de Phytosociologie (FIP). 5Now the International Association for Vegetation Science (IAVS) [43]. edition of the code was jointly prepared by the IAVS and the Fédération Internationale de Phytosociologie (FIP) [39]. 5. Now the International Association for Vegetation Science (IAVS). The Phylogenetic Code of Biological Nomenclature (PhyloCode) The idea of the PhyloCode was conceived in 2004. It aims at providing an alternative system for governing the application of names in ‘clades’, biological groups that consist of an ancestor (an organism, population, or species) and all of its descendants. The latest version is Version 6, published in 2020 [40]. APPENDIX 2. APPROVED LISTS OF BACTERIAL NAMES The Approved Lists of Bacterial Names consist of two Lists that were published on 1 January 1980 in the IJSB [40]: Approved List 1. Names of taxa above the rank of genus, pp. 231–238. Approved List 2. Names of genera, species, and subspecies, pp. 239–420. See also the Corrigenda (1984) [41] and the reprint of the Approved Lists (1989) [42]. For information about the history of the Approved Lists, see Sneath, 2005 [43]. APPENDIX 2. APPROVED LISTS OF BACTERIAL NAMES The Approved Lists of Bacterial Names consist of two Lists that were published on 1 January 1980 in the IJSB [41]: Approved List 1. Names of taxa above the rank of genus, pp. 231–238. Approved List 2. Names of genera, species, and subspecies, pp. 239–420. See also the Corrigenda (1984) [42] and the reprint of the Approved Lists (1989) [43]. For information about the history of the Approved Lists, see Sneath, 2005 [44]. APPENDIX 3. PUBLISHED SOURCES FOR NAMES OF PROKARYOTIC, ALGAL, PROTOZOAL, FUNGAL, AND VIRAL TAXA APPENDIX 3. PUBLISHED SOURCES FOR NAMES OF PROKARYOTIC, ALGAL, PROTOZOAL, FUNGAL, AND VIRAL TAXA 113 The following publications are among the major references for names of prokaryotic, algal, protozoal, fungal, and viral taxa. Following the introduction of the Approved Lists of Bacterial Names in 1980 [44-46], names published prior to 1980 that did not appear on either of the Approved Lists or the Corrigenda to the Approved Lists are not validly published unless subsequently validly published in accordance with the Rules of this Code. Information on many other names published prior to 1980 is found in the Index Bergeyana [30, 48]. Prokaryotic names validly published since 1980 are published in the IJSEM as articles, Notification Lists and Validation Lists [49, 50]. The first Validation List was published in Vol. 27, no. 3 of the IJSB in 1977; Notification Lists were first added in Vol. 41, no 3 of the IJSB in 1991. A comprehensive list of prokaryotic names, their status and their bibliographic history has been published as the Taxonomic Outline of Bacteria and Archaea [51]. Further information that is regularly updated is found online in the websites LPSN – List of Prokaryotic names with Standing in Nomenclature (www.bacterio.net; https://lpsn.dsmz.de/ [Accessed 29.7.2022]) and NamesforLife (www.namesforlife.com/search [Accessed 29.7.2022]) and in the following sources: for all groups of prokaryotes: Bergey’s Manual of Systematics of Archaea and Bacteria [52]. for pathovars and phytopathogenic bacteria: [53]. for cyanobacteria: [54]. for algae: [55–60]. for protozoa: [61–64]. for fungi: [65–69]. The following publications are among the major references for names of prokaryotic, algal, protozoal, fungal, and viral taxa. Following the introduction of the Approved Lists of Bacterial Names in 1980 [41-43], names published prior to 1980 that did not appear on either of the Approved Lists or the Corrigenda to the Approved Lists are not validly published unless subsequently validly published in accordance with the Rules of this Code. Information on many other names published prior to 1980 is found in the Index Bergeyana [45,46]. Prokaryotic names validly published since 1980 are published in the IJSEM as articles, Notification Lists and Validation Lists [47,48]. The first Validation List was published in Vol. 27, no. 3 of the IJSB in 1977; Notification Lists were first added in Vol. 41, no 3 of the IJSB in 1991. Updated information is found online on the website LPSN - List of Prokaryotic names with Standing in Nomenclature (www.bacterio.net; https://lpsn.dsmz.de/ (accessed: 4 October 2024 [TO BE UPDATED FURTHER] and in the following sources:  for all groups of prokaryotes: Bergey’s Manual of Systematics of Archaea and Bacteria [49].  for pathovars and phytopathogenic bacteria: [50].  for cyanobacteria: [51].  for algae: [52–57].  for protozoa: [58–61].  for fungi: [62,63].  for viruses: [64]  general: [65]. 114 for viruses: [70, 71]. general: [72]. Names of cyanobacterial taxa conserved or rejected under the International Code of Nomenclature for algae, fungi, and plants can be found in the appendices of that code [7]. APPENDIX 4. CONSERVED AND REJECTED NAMES OF PROKARYOTIC TAXA (Nomina taxorum conservanda et rejicienda) APPENDIX 4. CONSERVED AND REJECTED NAMES OF PROKARYOTIC TAXA (Nomina taxorum conservanda et rejicienda) List 1. Family names conserved and rejected by the Judicial Commission. List 2. Names of genera of prokaryotes conserved by the Judicial Commission. List 3. Specific epithets in names of species of prokaryotes conserved by the Judicial Commission. List 4. Names of classes of prokaryotes rejected by the Judicial Commission. List 5. Names of orders of prokaryotes rejected by the Judicial Commission. List 6. Names of genera and subgenera of prokaryotes rejected by the Judicial Commission. List 7. Specific and subspecific epithets in names of species and subspecies of prokaryotes rejected by the Judicial Commission. List 1. Conserved and rejected family names of prokaryotes (nomina familiarum conservanda et rejicienda) List 2. Conserved and rejected names of genera of prokaryotes (nomiina generum conservanda) List 3. Conserved specific epithets in names of species of prokaryotes (epitheta specifica conservanda) List 4. Rejected names of divisions of prokaryotes (nominia divisionum rejicienda) List 5. Rejected names of classes of prokaryotes (nomina classium rejicienda) List 6. Rejected names of subclasses of prokaryotes (nomina subclassium rejicienda) List 7. Rejected names of orders of prokaryotes (nomina ordinum rejicienda) List 8. Rejected names of genera and subgenera of prokaryotes nomina generum et subgenerum rejicienda) 115 List 9. Rejected specific and subspecific epithets in names of species and subspecies of prokaryotes (epitheta specifica et subspecifica rejicienda) The citations are (unless otherwise indicated) to the volumes, pages, and dates of the International Bulletin of Bacteriological Nomenclature and Taxonomy until vol. 15 (1965). From vol. 16 (1966) through vol. 49 (1999) the citations are for the International Journal of Systematic Bacteriology and thereafter of the International Journal of Systematic and Evolutionary Microbiology. The citations are (unless otherwise indicated) to the volumes, pages, and dates of the International Bulletin of Bacteriological Nomenclature and Taxonomy until vol. 15 (1965). From vol. 16 (1966) through vol. 49 (1999) the citations are for the International Journal of Systematic Bacteriology and thereafter of the International Journal of Systematic and Evolutionary Microbiology. List 1. Conserved and rejected family names of prokaryotes (nomina familiarum conservanda et rejicienda) List 1. Conserved and rejected family names of prokaryotes (nomina familiarum conservanda et rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 2. Conserved and rejected names of genera of prokaryotes (nomina generum conservanda) List 2. Conserved and rejected names of genera of prokaryotes (nomina generum conservanda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 3. Conserved specific epithets in names of species of prokaryotes (epitheta specifica conservanda) List 3. Conserved specific epithets in names of species of prokaryotes (epitheta specifica conservanda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 4. Rejected names of divisions of prokaryotes (nomina divisionum rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES 116 List 5 . Rejected names of classes of prokaryotes (nomina classium rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 6. Rejected names of subclasses of prokaryotes ( nomina subclassium rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 7. Rejected names of orders of prokaryotes (nomina ordinum rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES List 8. Rejected names of genera and subgenera of prokaryotes nomina generum et subgenerum rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES L ist 9. Rejected specific and subspecific epithets in names of species and subspecies of prokaryotes (epitheta specifica et subspecifica rejicienda) SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES APPENDIX 5. OPINIONS RELATING TO THE NOMENCLATURE OF PROKARYOTES APPENDIX 5. OPINIONS RELATING TO THE NOMENCLATURE OF PROKARYOTES SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES 117 APPENDIX 6. PUBLISHED SOURCES FOR RECOMMENDED MINIMAL STANDARDS FOR THE DESCRIPTION OF NEW TAXA OF PROKARYOTES APPENDIX 6. PUBLISHED SOURCES FOR RECOMMENDED MINIMAL STANDARDS FOR THE DESCRIPTION OF NEW TAXA OF PROKARYOTES SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES APPENDIX 7. PUBLICATION OF A NEW NAME APPENDIX 7. PUBLICATION OF A NEW NAME Valid publication of the name of a taxon (including a new combination) requires publication in the International Journal of Systematic and Evolutionary Microbiology (IJSEM) of (a) the name of the taxon, (b) a designation of a type for the new taxon, and (c) a description or a reference to an effectively published description of the taxon, whether in the IJSEM or in another publication. (1) The new name should be in the correct form. Generic and suprageneric names are single words in Latin form and spelled with an initial capital letter. Names of species are binary combinations in Latin form consisting of a generic name and a single, specific epithet; the latter spelled with an initial lowercase letter. Subspecific names are ternary combinations, consisting of the name of a species followed by the term “subspecies” (abbreviation: “subsp.”) and this followed by a single subspecific epithet. Names of taxa from the rank of order through tribe are formed by the addition of the appropriate suffix to the stem of the name of the type genus (see (5) below). The suffix for order is -ales, for suborder -ineae, for family -aceae, and for tribe -eae. The suffix for class is - ia, for subclass –idae. These endings are added to the stem of the name of the type genus of the type order of the class or subclass. Names of new phyla are formed by the addition of the suffix –ota to the stem of the name of one of the contained genera. Valid p ublication of the name of a taxon (including a new combination) requires publication in the International Journal of Systematic and Evolutionary Microbiology (IJSEM) of (a) the name of the taxon, (b) a designation of a type for the new taxon, and (c) a description or a reference to an effectively published description of the taxon, whether in the IJSEM or in another publication. (1) The new name must be in the correct form. Generic and suprageneric names are single words in Latin form and spelled with an initial capital letter. Names of species are binary combinations in Latin form consisting of a generic name and a single, specific epithet; the latter spelled with an initial lowercase letter. Subspecific names are ternary combinations consisting of the name of a species followed by the term “subspecies” (abbreviation: “subsp.”) and this followed by a single subspecific epithet. Names of taxa from the rank of order through tribe are formed by the addition of the appropriate suffix to the stem of the name of the type genus (see (5) below). The suffix for order is -ales, for suborder -ineae, for family -aceae, and for tribe -eae. The suffix for class is -ia, for subclass – idae. These endings are added to the stem of the name of the type genus of the type genus of the class or subclass. Names of new phyla are formed by the addition of the suffix –ota to the stem of the name of the type genus one of the contained genera. Names of new kingdoms are formed by the addition of the suffix -ati to the stem of the name of the type genus 118 Whenever possible, the title of the paper should include any new names or combinations that are proposed in the text. (2) New names are proposed by appending the phrase “species nova” (abbreviation: sp. nov.), “genus novum” (abbreviation: gen. nov.), “combinatio nova” (abbreviation: comb. nov.), or the like after the name or combination that is being proposed. Revival of names published prior to 1 January 1980 but not included in an Approved List may be effected by provisions in Rule 33. A list of abbreviations used in the description of new taxa is given in the following Table. one of the contained genera . Names of new domains are formed as plural of the last component of the name of one of the contained genera. Whenever possible, the title of the paper should include any new names or combinations that are proposed in the text. (2) New names are proposed by appending the phrase “species nova” (abbreviation: sp. nov.), “genus novum” (abbreviation: gen. nov.), “combinatio nova” (abbreviation: comb. nov.), or the like after the name or combination that is being proposed. Revival of names published prior to 1 January 1980 but not included in an Approved List may be effected by provisions in Rule 33. A list of abbreviations used in the description of new taxa is given in the following Table. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES (3) The name should not be a later homonym of a name previously validly published in the botanical and zoological literature (See Appendix 3 for published sources of names of plant and animal taxa.) (4) Rule 27(2)b states that the derivation (etymology) of a new name (and, if necessary, of a new combination) must be given. It is recommended to present the etymology, preceded by the proposed syllabification, in the style shown in the following hypothetical example of a new genus name: Thermalbibacter gen. nov. ( Therm. al. bi. bac’ter. Gr. fem. n. therme, heat; L. masc. adj. albus, white; N.L. masc. n. bacter, a rod; N.L. masc. n. Thermalbibacter, a white rod in a hot environment). (3) The name must not be a later homonym of a name previously validly published in the botanical and zoological literature (See Appendix 3 for published sources of names of plant and animal taxa and Rule 51b for exceptions.) (4) Rule 27(2)(b) states that the derivation (etymology) of a new name (and, if necessary, of a new combination) must be given. It is recommended to present the etymology, preceded by the proposed syllabification, in the style shown in the following hypothetical example from the (corrected) proposal of the new generic name Thermalbibacter Zhao et al. 2023: Thermalbibacter gen. nov. (Therm.al.bi.bac'ter, Gr. masc. adj. thermos, hot; L. masc. adj. albus, white; N.L. masc. n. bacter, a rod; N.L. masc. n. Thermalbibacter, a white rod from a hot environment). 119 The syllabification is printed in roman type, the stressed syllable is fo llowed by the apostrophe sign (′), and the last syllable is followed by a full stop. For guidelines on how to break names into syllables, see p. 246 in [100]. (5) The name must be accompanied by a description of the taxon or by a reference to an effectively published description of the taxon (see (7) below). (6) The nomenclatural type of a new taxon should be designated. In the case of species and subspecies, the type strain should be designated by the author’s strain number as well as the accession number, under which it is held by at least two culture collections located in different countries from which cultures of the strain are available without restrictions. A nomenclatural type is that constituent element of a taxon to which the name of a taxon is permanently attached. The type of a species or a subspecies is a strain, that of a genus is a species, and that of an order, suborder, family, or tribe is the genus on which name the higher taxon name is based (see one above). The type of a class or subclass is one of the contained orders. The type of a phylum is one of the contained genera. A type strain is one of the strains on which the author(s) who first described a named species or subspecies based the description of the species or subspecies, and which the author(s) or a subsequent author(s) designated as a type. The syllabification is printed in R oman type , the stre ssed syllable is followed by the apostrophe sign (‘), and the last syllable is followed by a full stop. For guidelines on how to break names into syllables, see [93]. (5) The name must be accompanied by a description of the taxon or by a reference to an effectively published description of the taxon (see (7) below). (6) The nomenclatural type of a new taxon must be designated. In the case of species and subspecies, the type strain must be designated by the author’s strain number as well as the accession number under which it is held by at least two culture collections located in different countries from which cultures of the strain are available without restrictions. A nomenclatural type is that constituent element of a taxon to which the name of a taxon is permanently attached. The type of a species or a subspecies is a strain, that of a genus or a subgenus is a species, and that of a domain, kingdom, phylum, class, subclass, order, suborder, family, or tribe is a genus. With few exceptions (provided for by Rule 8 and Rule 21b) the name of the higher taxon is based on the name of that genus. A type strain is one of the strains on which the authors who first described a named species or subspecies based the description of the species or subspecies, and which the authors or subsequent authors designated as a type. A neotype strain replaces a type strain which can no longer be found (Rule 18c) or is no longer viable [Rule 18a(2), Rule 30(3)]. The neotype must possess the characteristics as given in the original description; any deviations must be explained. A neotype strain must be proposed by an 120 A neotype strain replaces a type strain which can no longer be found (Rule 18c) or is no longer viable (Rule 18a(2), Rule 30(3)). The neotype should possess the characteristics as given in the original description; any deviations should be explained. A neotype strain must be proposed by an author in the IJSEM (proposed neotype) together with a reference (or references) to the first description and name for the microorganism (or to an Approved List, if appropriate), a description (or reference to a description) of the proposed neotype strain, and a record of the designation of the author(s) for the type strain and at least two culture collections from which cultures of the strain are available. The neotype strain becomes established 2 years after the date of publication in the IJSEM (established neotype). Any objections should be referred to the Judicial Commission within the first year after publication of the proposal. A neotype strain shall be proposed only after a careful search for original strains. If an original strain is subsequently discovered, the matter shall be referred immediately to the Judicial Commission. Allowance is made for replacement of an unsuitable type strain. (7) Descriptions of taxa should include the following information: (a) those characteristics which are essential for membership in the taxon, i.e., those characteristics which constitute the basic concept of the taxon; (b) those characteristics which qualify the taxon for membership in the next higher taxon; (c) the diagnostic characteristics, i.e., those characteristics which distinguish the taxon from closely related taxa; and (d) in the case of species, the total number of strains studied, and the strain designations should be given. From this information, the detailed results for each strain can be reconstructed without the full publication of the details for each strain. When appropriate, suitable photomicrographs and, if necessary, electron photomicrographs should be included as part of the description, to show morphological or anatomical characters that are pertinent to the author in the IJSEM (proposed neotype) together with a reference (or references) to the first description and name for the microorganism (or to an Approved List, if appropriate), a description (or reference to a description) of the proposed neotype strain, and a record of the designation of the author(s) for the type strain and at least two culture collections from which cultures of the strain are available. The neotype strain becomes established two years after the date of publication in the IJSEM (established neotype). Any objections must be referred to the Judicial Commission within the first year after publication of the proposal. A neotype strain shall be proposed only after a careful search for original strains. If an original strain is subsequently discovered, the matter shall be referred immediately to the Judicial Commission. Allowance is made for replacement of an unsuitable type strain. (7) Descriptions of taxa must include the following information: (a) those characteristics which are essential for membership in the taxon, i.e., those characteristics that constitute the basic concept of the taxon; (b) those characteristics that qualify the taxon for membership in the next higher taxon; (c) the diagnostic characteristics, i.e., those characteristics that distinguish the taxon from closely related taxa; and (d) in the case of species, the total number of strains studied, and the strain designations must be given. From this information, the detailed results for each strain can be reconstructed without the full publication of the details for each strain. When appropriate, suitable photomicrographs and, if necessary, electron photomicrographs should be included as part of the description, to show morphological or anatomical characters that are pertinent to the classification. Descriptions should conform, at least, to such proposed minimal standards for the description of new taxa in certain groups as have been approved by the ICSP Subcommittees on Taxonomy. 121 classification. Descriptions should co nform, at least, to such proposed minimal standards for the description of new taxa in certain groups as have been approved by the ICSP Subcommittees on Taxonomy. APPENDIX 8. PREPARATION OF A REQUEST FOR AN OPINION APPENDIX 8. PREPARATION OF A REQUEST FOR AN OPINI ON In cases wherein strict adherence to the rules of nomenclature would produce confusion or would not result in nomenclatural stability, exceptions to the rules may be requested of the Judicial Commission of the ICSP. Requests for Opinions must be accompanied by a comprehensively documented statement of the relevant facts. The Judicial Commission will consider all Requests for Opinions and should issue an Opinion in the IJSEM whether or not the proposal is accepted or rejected. The title of a manuscript should provide a concise statement of the contents of the manuscript. If an opinion of the Judicial Commission is requested, “Request for an Opinion” should appear as a subtitle. A Request for an Opinion submitted in an acceptable form, as determined by peer review, will be published in the IJSEM. If a request is not supported by adequate evidence, it will be returned to the author for revision. When an Opinion is challenged, the basis of the challenge must be stated and supported by a documented statement of the relevant facts. Requests for Opinions will be considered by the Judicial Commission within 6 months. Further information is found in Article 8 of the Statutes of the International Committee on Systematics of Prokaryotes. In cases wherein stric t adherence to the rules of nomenclature would produce confusion or would not result in nomenclatural stability, exceptions to the rules may be requested of the Judicial Commission of the ICSP. Requests for Opinions must be accompanied by a comprehensively documented statement of the relevant facts. The Judicial Commission will consider all Requests for Opinions and must issue an Opinion in the IJSEM whether or not the proposal is granted or denied. The title of a manuscript should provide a concise statement of the contents of the manuscript. If an opinion of the Judicial Commission is requested, “Request for an Opinion” should appear as a subtitle. The Judicial Commission recently published detailed guidelines to assist potential authors in deciding whether their concern should be the subject of a Request, and if so, in composing it with the greatest chance of success [5]. A Request for an Opinion submitted in an acceptable form, as determined by peer review, will be published in the IJSEM. If a request is not supported by adequate evidence, it will be returned to the author for revision. When an Opinion is challenged, the basis of the challenge must be stated and supported by a documented statement of the relevant facts. Requests for Opinions will be considered by the Judicial Commission within 6 months. Further information is found in Article 8 of the Statutes of the International Committee on Systematics of Prokaryotes. APPENDIX 9. ADVICE ON THE FORMATION OF NAMES AND ORTHOGRAPHY APPENDIX 9. ADVICE ON T HE FORMATION OF NAMES AND ORTHOGRAPHY 128 (b) Participles are treated as if they are adjectives, i.e., they fall under Rule 12c(1) of the Code. (c) Infinitive (also named ‘present’) participles in the singular do not change with gender. According to the four conjugations of Latin, they end in -ans (first conjugation, e.g. vorans devouring, from vorare to devour, voro I devour), - ens (second conjugation, e.g. inhibens inhibiting, from inhibere to inhibit, inhibeo I inhibit), -ens (third conjugation, e.g. exigens demanding, from exigere to demand, exigo I demand), -iens (third conjugation, i.e., faciens making, from facere to make, facio I make), -iens (fourth conjugation, e.g. oboediens obeying, from oboedire to obey, oboedio I obey). (d) Perfect participles change their endings with gender and are handled like adjectives of the first and second declension, e.g., aggregatus (masc.), aggregata (fem.), aggregatum (neut.) (aggregated, from aggregare to get together), flexus, flexa, flexum (bent, from flectere to bend), latus, lata, latum (carried, from the irregular verb ferre to carry), diminutus, diminuta, diminutum (smashed, from diminuere to smash). 3) Nominative nouns in apposition as specific epithets (a) In grammar, apposition means ‘the placing of a word or expression beside another so that the second explains and has the same grammatical construction as the first’; i.e., the added nominative noun has an explanatory specifying function for the generic name. Thus, Desulfovibrio gigas may be understood as Desulfovibrio dictus gigas and translates as ‘Desulfovibrio, called the giant’. (b) Participles are treated as if they are adjectives, i.e., they fall under Rule 12c(1) of the Code. (c) Infinitive (also named ‘present’) participles in the singular do not change with gender. According to the four conjugations of Latin, they end in -ans (first conjugation, i.e., vorans devouring, from vorare to devour, voro I devour), -ens (second conjugation, i.e., inhibens inhibiting, from inhibere to inhibit, inhibeo I inhibit), -ens (third conjugation, i.e., exigens demanding, from exigere to demand, exigo I demand), -iens (third conjugation, i.e., faciens making, from facere to make, facio, I make), -iens (fourth conjugation, i.e., oboediens obeying, from oboedire to obey, oboedio I obey). (d) Perfect participles change their endings with gender and are handled like adjectives of the first and second declension, e.g., aggregatus (masc.), aggregata (fem.), aggregatum (neut.) (aggregated, from aggregare to get together), flexus, flexa, flexum (bent, from flectere to bend), latus, lata, latum (carried, from the irregular verb ferre to carry), diminutus, diminuta, diminutum (smashed, from diminuere to smash). (3) Nominative nouns in apposition as specific epithets (a) In grammar, apposition means ‘the placing of a word or expression beside another so that the second explains and has the same grammatical construction as the first’; i.e., the added nominative noun has an explanatory specifying function for the generic name. Thus, Desulfovibrio gigas may be understood as Desulfovibrio dictus gigas and translates as ‘Desulfovibrio, called the giant’. 129 (b) All specific epithets ending with the Latin suffixes - cola (derived from incola, ‘the inhabitant, dweller’) and -cida (‘the killer’) are examples of such nominative nouns in apposition. 4) Genitive nouns as specific epithets (a) The singular genitive of nouns can be found in dictionaries. (b) If the plural genitive is preferred, as for example in Lactobacillus plantarum (‘of plants’), the declension of the noun should be determined, as plural genitives are different in different declensions [see F (3)]. Examples: Curtobacterium plantarum (first declension); Staphylococcus equorum (second declension); Bifidobacterium dentium (third declension); examples have not yet been found of the fourth and fifth declensions. (b) All specific epithets ending with the Latin suffixes - cola (derived from incola, ‘the inhabitant, dweller’) and -cida (‘the killer’) are examples of such nominative nouns in apposition. 4) Genitive nouns as specific epithets (a) The singular genitive of nouns can be found in dictionaries. (b) If the plural genitive is preferred, as for example in Paenibacillus plantarum (‘of plants’), the declension of the noun must be determined, as plural genitives are different in different declensions [see F (3)]. Examples: Curtobacterium plantarum (first declension); Staphylococcus equorum (second declension); Bifidobacterium dentium (third declension); examples have not yet been found of the fourth and fifth declensions. D. Formation of Prokaryote Names from Personal Names (1) Persons may be honoured by using their name in forming a generic name or a specific epithet. However, the Code recommends refraining from naming taxa after persons that are not connected with microbiology or, at least, with natural science [see Recommendations 10a(1) and 12c(3)]. (2) Latinization of personal names (Table 2). (a) It is good practice, where possible, to ask the person to be honoured by a scientific name for permission to use their name and to consider their preferences for how the name is Romanized and Latinized. D. Formation of Prokaryote Names from Personal Names (1) Persons may be honoured by using their name in forming a generic name or a specific epithet. However, the Code recommends refraining from naming taxa after persons that are not connected with microbiology or, at least, with natural science [see Recommendations 10a(1) and 12c(3)]. (2) Latinization of personal names (Table 2). (a) It is good practice, where possible, to ask the person to be honoured by a scientific name for permission to use their name and to consider their preferences for how the name is Romanized and Latinized. 130 (b) Authors should refrain from naming bacteria after themselves or co - authors in the same publication [see Recommendations 6(7) and 12c(3)]. (c) The formation of prokaryote names from personal names has no geopolitical meaning and cannot be used to express geopolitical claims [see General Consideration 8]. (d) More than one person can be honoured in a single generic name or epithet. Examples: Lechevalieria after Hubert and Mary Lechevalier. (e) When the personal name is already a Latin name, no further Latinization is needed, e.g., Julia, Victoria, Leo. When originating from languages written in non-Roman scripts, personal names should be rendered in the Roman alphabet according to an existing romanization scheme for the namebearer’s language or, where no such scheme exists, through transcription of the spoken form. (f) Hyphens and white spaces must be removed from any components of a personal name used to build a scientific name [see Rule 12a]. Diacritics must be removed according to the conventions of the language of the namebearer, e.g., German surnames Höffner and Müller become Hoeffner and Mueller, whereas the Turkish surname Özgür becomes Ozgur and the Finnish surname Törönen becomes Toronen [see Rule 64]. (g) A Romanized derivative of the personal name is used to create a Latinized stem to which suffixes can be added or which can be used in compound word formation. The choice of which components of the personal name are used to create the Latinized stem should consider the wishes of the person being honoured, relevant traditions (e.g., respecting (b) Authors should refrain from naming bacteria after themselves or co - authors in the same publication [see Recommendations 6(7) and 12c(3)]. (c) The formation of prokaryote names from personal names has no geopolitical meaning and cannot be used to express geopolitical claims [see General Consideration 8]. (d) More than one person can be honoured in a single generic name or epithet. Examples: Lechevalieria after Hubert and Mary Lechevalier and kimseyorum, after Lynn S. and Robert B. Kimsey. (e) When the personal name is already a Latin name, no further Latinization is needed, e.g., Julia, Victoria, Leo. When originating from languages written in non-Roman scripts, personal names should be rendered in the Roman alphabet according to an existing romanization scheme for the name-bearer’s language or, where no such scheme exists, through transcription of the spoken form. (f) Hyphens and white spaces must be removed from any components of a personal name used to build a scientific name [see Rule 12a]. Diacritics must be removed according to the conventions of the language of the name-bearer, e.g., German surnames Höffner and Müller become Hoeffner and Mueller, whereas the Turkish surname Özgür becomes Ozgur and the Finnish surname Törönen becomes Toronen [see Rule 64]. (g) A Romanized derivative of the personal name is used to create a Latinized stem to which suffixes can be added or which can be used in compound word formation. The choice of which components of the personal name are used to create the Latinized stem should consider the wishes of the person being honoured, relevant traditions (e.g., respecting 131 cultures where multiple surnames are used or none) and the goal of creating agreeable user-friendly scientific names (see Recommendation 6). When someone has multiple surnames, just one or two of these can be used to honour them. Example: Boudabousia, honouring Abdellatif Boudabous Chihi, Streptomyces lunalinharesii honouring Luiz Fernando de Toledo Luna Linhares, Citrobacter murliniae honouring Alma C. McWhorter-Murlin. (h) Although a surname is most often used, generic names or specific epithets can also be formed from given names. Examples: Erwinia after Erwin Smith, Jutongia after Wú Jùtōng, Staphylococcus arlettae after Arlette van de Kerckhove and Nocardia bhagyanarayanae honouring Bhagyanarayana Gaddam. Scientific names can also be formed from given names placed before or after surnames conjoined without a connecting vowel. Examples: Elizabethkingia honouring Elizabeth King, Yonghaparkia honouring Yong-ha Park and Gaoshiqia honouring Gāo Shíqí. (i) Kinship prefixes (e.g., Ó/ Ní, Mac/Mc, ibn/bin/bint, Abu, ap and Ben) and particles and articles (e.g., al, de, le, van and von) may be omitted or included in the Latinized stem. Examples: Rochalimaea after da Rocha-Lima and Leclercia after Le Clerc. However, honorific titles (e.g., Sir, Sri and Sheikh) are not usually included in prokaryote names. (j) To render the Latinized stems easy to pronounce, simplified or truncated forms of personal names may be adopted. Examples: chauvoei after Chauveau; Simkania after Simona Kahane and jeikeium after Johnson and Kaye. Additional vowels may be added (e.g., macginleyi after Kenneth John McGinley). Intentional Latinizations involving changes in orthography of personal names must be preserved [see Rule 60]. cultures where multiple surnames are used or none) and the goal of creating agreeable user-friendly scientific names (see Recommendation 6). When someone has multiple surnames, just one or two of these can be used to honour them. Example: Boudabousia, honouring Abdellatif Boudabous Chihi, Streptomyces lunalinharesii honouring Luiz Fernando de Toledo Luna Linhares, Citrobacter murliniae honouring Alma C. McWhorter-Murlin. (h) Although a surname is most often used, generic names or specific epithets can also be formed from given names. Examples: Erwinia after Erwin Smith, Jutongia after Wú Jùtōng, Staphylococcus arlettae after Arlette van de Kerckhove and Nocardia bhagyanarayanae honouring Bhagyanarayana Gaddam. Scientific names can also be formed from given names placed before or after surnames conjoined without a connecting vowel. Examples: Elizabethkingia honouring Elizabeth King, Yonghaparkia honouring Yong-ha Park and Gaoshiqia honouring Gāo Shíqí. (i) Kinship prefixes (e.g., Ó/ Ní, Mac/Mc, ibn/bin/bint, Abu, ap and Ben) and particles and articles (e.g., al, de, le, van and von) may be omitted or included in the Latinized stem. Examples: Rochalimaea after da RochaLima and Leclercia after Le Clerc. However, honorific titles (e.g., Sir, Sri and Sheikh) are not usually included in prokaryote names. (j) To render the Latinized stems easy to pronounce, simplified or truncated forms of personal names may be adopted. Examples: chauvoei after Chauveau; Simkania after Simona Kahane and jeikeium after Johnson and Kaye. Additional vowels should be added if needed (e.g., macginleyi after Kenneth John McGinley). Intentional Latinizations involving changes in orthography of personal names must be preserved [see Rule 60]. 132 (k) When the personal name ends in - a , the name should be treated as a first-declension Latin noun, where the stem is formed by removing the -a. When the personal name is a Latin name that ends in -us, the name should be treated as a second-declension Latin noun, where the stem is formed by removing the -us. When the personal name ends in -o, the name should be treated as a third-declension Latin noun, where the stem is formed by adding -n to give a genitive form ending in -onis. (l) When a family name is used, there is the option to augment the stem by adding -i to the end of a family name, e.g., as in the epithet youngii in Xanthomonas youngii, after John Young. However, this is optional, as seen in Citrobacter youngae, which honours Viola Young. Stem augmentation is generally avoided when the Latinized stem ends in a vowel, e.g., the epithet voltae not voltiae from Volta; sakazakii not sakazakiii from Sakazaki, and is inappropriate for components other than family names. Some authorities suggest stem augmentation should be avoided for names ending in -er, e.g., in the genus name Buchnera or species epithet brenneri. However, for consistency, the suffix -ia can be used when forming genus names in such cases e.g., Listeria or Burkholderia. (k) When the personal name ends in - a , the name should be treated as a first-declension Latin noun, where the stem is formed by removing the -a. When the personal name is a Latin name that ends in -us, the name should be treated as a second-declension Latin noun, where the stem is formed by removing the -us. When the personal name ends in -o, the name should be treated as a third-declension Latin noun, where the stem is formed by adding -n to give a genitive form ending in -onis. (l) When a surname is used, there is the option to augment the stem by adding -i to the end of a surname, e.g., as in the epithet youngii in Xanthomonas youngii, after John Young. However, this is optional, as seen in Citrobacter youngae, which honours Viola Young. Stem augmentation is generally avoided when the Latinized stem ends in a vowel, e.g., the epithet curieae not curieiae from Curie; sakazakii not sakazakiii from Sakazaki, and is inappropriate for components other than surnames. Some authorities suggest stem augmentation should be avoided for names ending in -er, e.g., in the generic name Buchnera or specific epithet brenneri. However, for consistency, the suffix -ia can be used when forming genus names in such cases e.g., Listeria or Burkholderia. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES (3) Personal names in generic names (Table 3) There are three suggested ways to form a generic name from the latinized stem of a personal name: (a) Directly, by adding the feminine ending -ia (or -a if the latinized stem ends in e, i or u, or -aea when the original personal name ends in -a). (3) Personal names in generic names (Table 3) There are three suggested ways to form a generic name from the Latinized stem of a personal name: (a) directly, by adding the feminine ending -ia (or -a if the Latinized stem ends in e, i or u, or -aea when the original personal name ends in -a). 133 (b) A s a diminutive, usually by adding the feminine ending - ella to the stem. When the stem ends in -e, the final letter should be omitted when forming diminutives, e.g., in forming Brucella from the personal name Bruce. When digraph -ee or the vowel -y occurs at the end of personal names, this may be latinized as i when forming diminutives. Examples: Cowdria and Roseburia from Cowdry and Rosebury or the species epithet asburiae after the family name Fife-Asbury. (c) By using a stem derived from a personal name as a word element in a compound name. Here the stem is linked, as needed, to the following word element by a connecting vowel. Example: Youngimonas, built from the stem young- (derived from the family name Young without stem augmentation), the connecting vowel -i and N.L. fem. n. monas. (b) as a diminutive, usually by adding the feminine ending - ella to the stem. When the stem ends in -e, the final letter should be omitted when forming diminutives, e.g., in forming Brucella from the personal name Bruce. When digraph -ee or the vowel -y occurs at the end of personal names, this may be Latinized as i when forming diminutives. Examples: Cowdria and Roseburia from Cowdry and Rosebury or the specific epithet asburiae after the surname Fife-Asbury. (c) by using a stem derived from a personal name as a word element in a compound name. Here the stem is linked, as needed, to the following word element by a connecting vowel. Example: Youngimonas or Youngiimonas, built from the stem young- (derived from the surname Young with stem augmentation), optionally the connecting vowel -i, and N.L. fem. n. monas. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES (4) Personal names in specific epithets (Table 4) Two possibilities exist to form specific epithets from personal names: (i) Creation of a genitive noun by adding an inflectional ending to the latinized stem, so that an epithet is formed with the meaning of ‘pertaining to the person being honoured’. The inflectional ending is chosen to reflect the sex of the person to be honoured: typically the feminine ending -ae is used for a female or the masculine or neuter ending -i is used for a male or non-binary individual, except where a male name belongs to first declension, e.g. voltae from Volta or a name from a female belongs to the second declension, e.g. pistorii to honour a female with the surname Pistorius or where a name of any gender has been assigned to the third (4) Pers onal names in specific epithets (Table 4) Two possibilities exist to form specific epithets from personal names (i) creation of a genitive noun by addition of an inflectional ending to the Latinized stem so that an epithet is formed with the meaning of ‘pertaining to the person being honoured’. The inflectional ending is chosen to reflect the sex of the person to be honoured: typically the feminine ending -ae for a female or the masculine or neuter ending -i for a male individual, except where a male name belongs to first declension, e.g., voltae from Volta or a name from a female belongs to the second declension, e.g., pistorii to honour a female with the surname Pistorius or where a name of any gender has been assigned to the third declension, e.g., mayonis after Mark 134 declension, e.g. mayonis after Mark Mayo. Where the personal name resembles a Latin genitive, it may be used unchanged as a species epithet, e.g. imshenetskii to honour Aleksandr Imshenetskii. (ii) Creation of an adjectival form by adding the endings -anus (masculine), - ana (feminine) or -anum (neuter) to the stem according to gender of the genus name. Note: The changes proposed in this version of Section D take effect on 1 January 2025 and are not retroactive. Names validly published before that date that do not comply with this version of Section D may not be considered to be misspelled for that reason. Mayo. Where the personal name resembles a Latin genitive, it may be used unchanged as a specific epithet, e.g., imshenetskii to honour Aleksandr Imshenetskii, if it can be formed as described above. (ii) creation of an adjectival form by adding the endings -anus (masculine), -ana (feminine) or -anum (neuter) to the stem according to gender of the generic name. Note: The changes proposed in this version of section D take effect on 1 January 2025 and are not retroactive. Spellings of names that were validly published before that date and do not comply with this version of Section D may not be corrected for that reason. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES E. Formation of Prokaryote Names from Geographical Names (1) The formation of prokaryote names from geographical names has no geopolitical meaning, i.e., such names cannot be used to express geopolitical claims (see General Consideration 8). (2) Similar to personal names (Table 2 of Appendix 9), names of locations can be used to form generic names of the feminine gender. The preferred ending of such names is –ia or (diminutive form) –ella. Examples are shown in Table 5. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES Not e: Basilia (Basilia, the Latin name of Basel, Switzerland) would be the preferred form instead of Basilea. Scandinavia would be the preferred form Note 1 : Basilia (Basilia, the Latin name of Basel, Switzerland) would be the preferred form instead of Basilea. Scandinavia would be the preferred 135 instead of Scandinavium . Instead of Nevskia , named after the Neva R ver, Russia, Nevia would be the preferred name. Similar to personal names (see Table 3 of Appendix 9 in the 2022 revision of the ICNP [1]), names of geographical locations can be used to form compound generic names. The guidelines are presented in Table 6. form instead of Scandinavium . Instead of Nevskia , named after the Neva Rver, Russia, Nevia would be the preferred name. Similar to personal names (see Table 3 of Appendix 9 in the 2022 revision of the ICNP [1]), names of geographical locations can be used to form compound generic names. The guidelines are presented in Table 6. SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES Note . Turicicella would be the preferred form instead of Turicella . ‘Candidatus Kapibacterium’ (Motse Kapa in the Sesotho language) would be the preferred form instead of ‘Candidatus Kapaibacterium’ or ‘Candidatus Kapabacteria’. ‘Candidatus Macondonimonas’ (Macondo Prospect, Gulf of Mexico, and Macondo, a fictional town in A Hundred Years of Solitude by G. García Márquez) would be the preferred form instead of ‘Candidatus Macondimonas’. Note also that after a Greek geographical location, –o is used as connecting vowel. Note. The recommendations and rules for specific epithets as given above are also applicable for genus names, i.e., when the name of location such as above lends itself to translation into Latin, it can be further used for the formation of genus names following the guidelines in Table 5 or 6. Examples: Flavimaricola (from Mare Flavum, the Yellow Sea) and Meridianimaribacter (from Mare Meridianum, the South Sea). (3) Unlike epithets derived from personal names, epithets created on the basis of geographical names should not be formed as nouns in the genitive case, but as adjectives. They usually are constructed by adding the ending – ensis (masculine or feminine gender) or -ense (neuter gender) to the geographical name and in agreement with the latter’s gender. Only if the Note 2 . Turicicella would be the preferred form instead of Turicella . ‘Candidatus Kapibacterium’ (Motse Kapa in the Sesotho language) would be the preferred form instead of ‘Candidatus Kapaibacterium’ or ‘Candidatus Kapabacteria’. ‘Candidatus Macondonimonas’ (Macondo Prospect, Gulf of Mexico, and Macondo, a fictional town in A Hundred Years of Solitude by G. García Márquez) would be the preferred form instead of ‘Candidatus Macondimonas’. Note also that after a Greek geographical location, –o is used as connecting vowel. Note 3. The recommendations and rules for specific epithets as given above are also applicable for generic names, i.e., when the name of location such as above lends itself to translation into Latin, it can be further used for the formation of generic names following the guidelines in Table 5 or 6. Examples: Flavimaricola (from Mare Flavum, the Yellow Sea) and Meridianimaribacter (from Mare Meridianum, the South Sea). (3) Unlike epithets derived from personal names, epithets created on the basis of geographical names should not be formed as nouns in the genitive case, but as adjectives. They usually are constructed by adding the ending –ensis (masculine or feminine gender) or -ense (neuter gender) to the geographical name and in agreement with the latter’s gender. Only if the 136 name of the locality ends in - a or - e or - en , are these letters dropped before adding -ensis/-ense (e.g., jenensis from Jena, californiensis from California, drentensis from Drente, bremensis from Bremen). If the locality’s name ends in -o, the ending becomes -nensis/-nense (e.g., the name of the Japanese city Sapporo: sapporonensis, sapporonense). (4) Quite a number of localities in the Old World (Europe, Asia, Africa) have classical Greek, Latin or medieval Latin names and adjectives derived from these: aegyptius (Egypt), africanus (Africa), arabicus (Arabia), asiaticus (Asia), balticus (Baltic Sea), bavaricus (Bavaria), bretonicus (Brittany), britannicus (Britain), europaeus (Europe), frisius (Friesland), gallicus (France), germanicus (Germany), graecus (Greece), hellenicus (Hellas, classical Greece), helveticus (Switzerland), hibernicus (Ireland), hispanicus (Spain), hungaricus (Hungary), ibericus (Spain/Portugal, the Iberian peninsula), indicus (India), italicus (Italy), mediterraneus (Mediterranean Sea), persicus (Persia, Iran), polonus (Poland), rhenanus (Rhineland), romanus (Rome), saxonicus (Saxony), etc. Neo-Latin names were given also to many other non-European parts of the world, so adjectives like americanus (America), antarcticus (‘southern’ in classical Latin) (Antarctica), australicus (Australia), cubanus (Cuba), mexicanus (Mexico), japonicus (Japan), etc. were introduced. Wherever such older adjectives exist, they may be used as specific epithets to indicate geographical origins. (5) European and Mediterranean cities and places of classical times may have had quite different names than today, e.g., Lucentum (Alicante, Spain), Argentoratum (Strasbourg, France), Lutetia (Paris, France), Traiectum (Utrecht, Netherlands), Ratisbona (Regensburg, Germany), Eboracum (York, UK), Londinium (London, UK) and Hafnia (København, Denmark), which lead to the respective adjectives lucentensis, argentoratensis, lutetiensis, name of the locality ends in - a or - e or - en , are these letters dropped before adding -ensis/-ense (e.g., jenensis from Jena, californiensis from California, drentensis from Drente, bremensis from Bremen). If the locality’s name ends in -o, the ending becomes -nensis/-nense (e.g., the name of the Japanese city Sapporo: sapporonensis, sapporonense). (4) Quite a number of localities in the Old World (Europe, Asia, Africa) have classical Greek, Latin or medieval Latin names and adjectives derived from these: aegyptius (Egypt), africanus (Africa), arabicus (Arabia), asiaticus (Asia), balticus (Baltic Sea), bavaricus (Bavaria), bretonicus (Brittany), britannicus (Britain), europaeus (Europe), frisius (Friesland), gallicus (France), germanicus (Germany), graecus (Greece), hellenicus (Hellas, classical Greece), helveticus (Switzerland), hibernicus (Ireland), hispanicus (Spain), hungaricus (Hungary), ibericus (Spain/Portugal, the Iberian peninsula), indicus (India), italicus (Italy), mediterraneus (Mediterranean Sea), persicus (Persia, Iran), polonus (Poland), rhenanus (Rhineland), romanus (Rome), saxonicus (Saxony), etc. Neo-Latin names were given also to many other non-European parts of the world, so adjectives like americanus (America), antarcticus (‘southern’ in classical Latin) (Antarctica), australicus (Australia), cubanus (Cuba), mexicanus (Mexico), japonicus (Japan), etc. were introduced. Wherever such older adjectives exist, they may be used as specific epithets to indicate geographical origins. (5) European and Mediterranean cities and places of classical times may have had quite different names than today, e.g., Lucentum (Alicante, Spain), Argentoratum (Strasbourg, France), Lutetia (Paris, France), Traiectum (Utrecht, Netherlands), Ratisbona (Regensburg, Germany), Eboracum (York, UK), Londinium (London, UK) and Hafnia (København, Denmark), which lead to the respective adjectives lucentensis, 137 traiectensis , ratisbonensis , eboracensis , londiniensis and hafniensis . Numerous additional examples are listed in https://en.wikipedia. org/wiki/Category:Lists _of_Latin_place_names (accessed: 4 October 2024 [TO BE UPDATED FURTHER]). Alternatively, the Neo-Latin adjectives of the modern names may be used: alicantensis, strasbourgensis, parisensis, utrechtensis, regensburgensis, yorkensis, londonensis, kobenhavnensis, respectively. (6) Many localities (mostly lakes, rivers, seas, islands, capes, rocks, mountains or valleys, but also some cities and towns) have names that consist of two words, usually an adjective and a noun (e.g., Deep Lake, Black Sea, Red River, Rio Grande, Long Island, Blue Mountain, Baton Rouge, Santa Cruz, Saint Germain, Sankt Georgen, etc.) or two nouns (e.g., Death Valley, Lake Windermere, Loch Ness, Martha’s Vineyard, Ayers Rock, Woods Hole, Cape Cod, Monte Carlo, etc.). The formation of specific epithets from the names of such localities may pose a problem, as the use of the adjectival suffix -ensis, -ense may lead to rather strange looking or awkward constructions, such as ‘deeplakensis’ or ‘bluemountainense’, although they would be formally correct. If the name of a locality lends itself to translation into Latin, specific epithets may be formed, as well as genitive nouns of the two components and concatenating them without hyphenation, such as the existing lacusprofundi (of Deep Lake), marisnigri (of the Black Sea), marismortui (of the Dead Sea) or, of two nouns, vallismortis (of Death Valley). See also Section A (1) (b) above. (7) The inclusion of articles (such as, the, el, o, il, le, la, a, de, der, die, das, den, het or their plurals the, los, las, os, as, les, ils, gli, le, de, die, ‘s, etc.) as they are used for locations in several languages (e.g., La Paz, El Ferrol, El Alamein, Le Havre, The Netherlands, Die Schweiz, Den Haag, ‘s Hertogenbosch, Los Angeles, etc.) should be avoided. argentoratensis , lutetiensis , traiectensis , ratisbonensis , eboracensis , londiniensis and hafniensis. Numerous additional examples are listed in https://en.wikipedia. org/wiki/Category:Lists _of_Latin_place_names (accessed: 4 October 2024 [TO BE UPDATED FURTHER]). Alternatively, the Neo-Latin adjectives of the modern names may be used: alicantensis, strasbourgensis, parisensis, utrechtensis, regensburgensis, yorkensis, londonensis, kobenhavnensis, respectively. (6) Many localities (mostly lakes, rivers, seas, islands, capes, rocks, mountains or valleys, but also some cities and towns) have names that consist of two words, usually an adjective and a noun (e.g., Deep Lake, Black Sea, Red River, Rio Grande, Long Island, Blue Mountain, Baton Rouge, Santa Cruz, Saint Germain, Sankt Georgen, etc.) or two nouns (e.g., Death Valley, Lake Windermere, Loch Ness, Martha’s Vineyard, Ayers Rock, Woods Hole, Cape Cod, Monte Carlo, etc.). The formation of specific epithets from the names of such localities may pose a problem, as the use of the adjectival suffix -ensis, -ense may lead to rather strange looking or awkward constructions, such as ‘deeplakensis’ or ‘bluemountainense’, although they would be formally correct. If the name of a locality lends itself to translation into Latin, specific epithets may be formed, as well as genitive nouns of the two components and concatenating them without hyphenation, such as the existing lacusprofundi (of Deep Lake), marisnigri (of the Black Sea), marismortui (of the Dead Sea) or, of two nouns, vallismortis (of Death Valley). See also Section A (1) (b) above. (7) The inclusion of articles (such as, the, el, o, il, le, la, a, de, der, die, das, den, het or their plurals the, los, las, os, as, les, ils, gli, le, de, die, ‘s, etc.) as they are used for locations in several languages (e.g., La Paz, El Ferrol, El Alamein, Le Havre, The Netherlands, Die Schweiz, Den Haag, ‘s Hertogenbosch, Los Angeles, etc.) should be avoided. 144 The term infrasubspecific subdivision (or division) has been used in two ways, i.e., to denote both terms and taxa. It is preferable to distinguish them as given below. Infrasubspecific “subdivision” has been used rather than “division” to avoid any confusion with the taxonomic category “division” (divisio) used in the botanical and the zoological nomenclature. Note. Infrasubspecific subdivisions are not arranged in any order of rank and may overlap one another. (1) Infrasubspecific taxa. An infrasubspecific taxon is one strain or a set of strains showing the same or similar properties, and treated as a taxonomic group. Example: Staphylococcus aureus phagovar 81. The sets of properties used may be of a similar kind but are not necessarily the same. Example: The susceptibility to a different phage may be used to define another phagovar of Staphylococcus aureus, e.g., phagovar 42D. Infrasubspecific taxa based on different sets of properties may overlap; e.g., one serovar may contain strains belonging to different phagovars. Example: Salmonella typhi serovars, phagovars, and biovars. (2) Infrasubspecific terms. An infrasubspecific term is used to refer to the kinds of taxa below subspecies. Examples: serovar, chemovar, forma specialis. The term infrasubspecific subdivision (or division) has been used in two ways to denote both terms and taxa. It is preferable to distinguish them as given below. Infrasubspecific “subdivision” has been used rather than “division” to avoid any confusion with the taxonomic category “division” (divisio) used in the botanical and the zoological nomenclature. Note. Infrasubspecific subdivisions are not arranged in any order of rank, and may overlap one another. (1) Infrasubspecific taxa. An infrasubspecific taxon is one strain or a set of strains showing the same or similar properties, and treated as a taxonomic group. Example: Staphylococcus aureus phagovar 81. The sets of properties used may be of a similar kind but are not necessarily the same. Example: The susceptibility to a different phage may be used to define another phagovar of Staphylococcus aureus, e.g., phagovar 42D. Infrasubspecific taxa based on different sets of properties may overlap; e.g., one serovar may contain strains belonging to different phagovars. Example: Salmonella enterica serovars, phagovars, and biovars. (2) Infrasubspecific terms. An infrasubspecific term is used to refer to the kinds of taxa below subspecies. 145 If a species has not been divided into subspecies, the infrasubspecific terms may be applied to other subdivisions within that species. The subdivisions so named would still be infrasubspecific subdivisions for nomenclatural purposes until they may be raised to subspecific or specific rank. Example: Serovars of Erysipelothrix rhusiopathiae. (3) Use of other terms. Infrasubspecific form has been used to refer to a bacterial strain, although this use should be avoided. A culture of prokaryotes is a population of bacterial cells in a given place at a given time, e.g., in this test tube or on that agar plate. It may have a long duration, e.g., desiccated cultures. A clone is a population of prokaryotic cells derived from a single parent cell. A strain is made up of the descendants of a single isolation in pure culture. A strain is usually made up of a succession of cultures and is often derived from a single colony. The number of cells which gave rise to the original colony is often unknown. Most prokaryotic strains are not known to be clones. Individual is a term with little meaning in bacteriology although it has been applied to a single prokaryotic cell or to a bacterial strain; it is best to avoid the use of this term. B. Infrasubspecific terms Examples: serovar, chemovar, forma specialis . If a species has not been divided into subspecies, the infrasubspecific terms may be applied to other subdivisions within that species. The subdivisions so named would still be infrasubspecific subdivisions for nomenclatural purposes until they may be raised to subspecific or specific rank. Example: serovars of Erysipelothrix rhusiopathiae. (3) Use of other terms. Infrasubspecific form has been used to refer to a bacterial strain, although this use should be avoided. A culture of prokaryotes is a population of bacterial cells in a given place at a given time, e.g., in this test tube or on that agar plate. It may have a long duration, e.g., desiccated cultures. A clone is a population of prokaryotic cells derived from a single parent cell. A strain is made up of the descendants of a single isolation in pure culture. A strain is usually made up of a succession of cultures and is often derived from a single colony. The number of cells that gave rise to the original colony is often unknown. Individual is a term with little meaning in bacteriology although it has been applied to a single prokaryotic cell or to a bacterial strain; it is best to avoid the use of this term. B. Infrasubspecific Terms 146 The table below contains some of the terms that are commonly used; the preferred name appears in the first column. The introduction of the suffix “- var” or “-form” to replace “-type” is recommended to avoid confusion with the strict use of the term ‘type’ to mean nomenclatural type (see Rule 15). The table below contains some of the terms that are commonly used, and the preferred name appears in the first column. The introduction of the suffix “-var” or “-form” to replace “-type” is recommended to avoid confusion with the strict use of the term “type” to mean nomenclatural type (see Rule 15). SEE SEPARATE FILE WITH TABLES SEE SEPARATE FILE WITH TABLES The term “type” in prokaryotic biology (e.g., phenotype, genotype, serotype, etc.) should not be confused with the strictly nomenclatural use of the term, type (Principle 5 and Chapter 3, Section 4). The term “group” is informal and has no nomenclatural standing. It may prove useful to designate informally a set of organisms having certain characteristics in common, provided that it is used with care and exact definition to avoid ambiguity. It should not be used to avoid the use of the correct name of a taxon such as genus or species. However, it may be useful when the bacteriologist does not wish to give a formal name to a set of prokaryotes until further studies have been made but wishes to publish his results and seek the opinion of others. Example: “IID group,” later named Cardiobacterium hominis. C. Nomenclature of Infrasubspecific Taxa An infrasubspecific taxon is designated or cited by the name of the species followed by the infrasubspecific term used to designate this infrasubspecific subdivision followed by the infrasubspecific designation. The term “type” in prokaryotic biology (e.g., phenotype, genotype, serotype, etc.) must not be confused with the strictly nomenclatural use of the term, type (Principle 5 and Chapter 3, Section 4). The term “group” is informal and has no nomenclatural standing. It may prove useful to designate informally a set of organisms having certain characteristics in common, provided that it is used with care and exact definition to avoid ambiguity. It must not be used to avoid the use of the correct name of a taxon such as genus or species. However, it may be useful when the bacteriologist does not wish to give a formal name to a set of prokaryotes until further studies have been made but wishes to publish his results and seek the opinion of others. Example: “IID group,” later named Cardiobacterium hominis. C. Nomenclature of Infrasubspecific Taxa An infrasubspecific taxon is designated or cited by the name of the species followed by the infrasubspecific term used to designate this infrasubspecific subdivision followed by the infrasubspecific designation. 147 Example: Staphylococcus aureus phagovar 81. Reference strains of infrasubspecific taxa may be designated. There are many ways that infrasubspecific taxa may be designated; among these are the following: latinized words, e.g., cerealis in Xanthomonas translucens f.sp. cerealis; vernacular names or words, e.g., rough phase; numbers, letters, or formulae, e.g., phagovar 42D in Staphyloccocus aureus phagovar 42D. D. Nomenclature of Strains A strain may be designated in any manner, e.g., by the name of an individual, by a locality, or by a number. Strain designations (e.g., strain collection accession numbers) should be preserved to ensure the ‘chain of custody’ of prokaryotes that are presumed to be the same but may demonstrate different features. Example: Staphylococcus aureus phagovar 81. Reference strains of infrasubspecific taxa may be designated. There are many ways that infrasubspecific taxa may be designated; among these are the following: Latinized words, e.g., cerealis in Xanthomonas translucens f.sp. cerealis; vernacular names or words, e.g., rough phase; numbers, letters, or formulae, e.g., phagovar 42D in Staphyloccocus aureus phagovar 42D. . D. Nomenclature of Strains A strain may be designated in any manner, e.g., by the name of an individual, by a locality, or by a number. Strain designations (e.g., strain collection accession numbers) must be preserved to ensure the ‘chain of custody’ of prokaryotes that are presumed to be the same but may demonstrate different features. APPENDIX 11. THE PROVISIONAL STATUS CANDIDATUS APPENDIX 11. THE PROVISIONAL STATUS CANDIDATUS Introduction of the status called Candidatus was first proposed by Murray and Schleifer in 1994 [118]. The provisional status Candidatus was intended for putative taxa of any rank that could not be described in sufficient detail to warrant establishment of a novel taxon, usually because of the absence of a pure culture. Following discussions of the International Committee on Systematics of Bacteria (ICSB; now the International Committee on Systematics of Prokaryotes, ICSP) [119], further guidelines were published for Candidatus taxa in 1995 [120]. Introduction of the status called Candidatus wa s first proposed by Murray and Schleifer in 1994 [110]. The provisional status Candidatus was intended for putative taxa of any rank that could not be described in sufficient details to warrant establishment of a novel taxon, usually because of the absence of a pure culture. Following discussions of the International Committee on Systematics of Bacteria (ICSB; now the International Committee on Systematics of Prokaryotes, ICSP) [111], further guidelines were published for Candidatus taxa in 1995 [112]. 148 This status should be used for describing prokaryotic taxa for which more than a nucleic acid sequence is available but for which the requirements for valid publication of a name according to the Code are not met. The following information should be included in the description of a Candidatus taxon: (a) Genomic information, i.e., nucleic acid sequences apt to determine the phylogenetic position of the organism. (b) All information so far available on structure and morphology (appropriate illustration), physiology and metabolism, reproductive features, the natural environment, in which the organism can be identified by in situ hybridization or similar techniques for cell detection and identification, and any other available and suitable information. A name of an organism in the status of Candidatus consists of the word Candidatus, followed by a name, based on one of the ranks defined in this Code (species, genus, family, etc.), formed in accordance with the nomenclature rules of the Code and its etymology appendix (Appendix 9); see also [121]. Examples: Candidatus Methanoflorentaceae (family rank), Candidatus Methanoflorens (genus rank), Candidatus Methanoflorens stordalenmirensis (species rank). Note that the word Candidatus, but not the name that follows, is printed in italics. A Candidatus name is, by definition, a preliminary name and, therefore, has no standing in prokaryote nomenclature. A proposal to include names of This status should be used for describing prokaryotic taxa for which more than a nucleic acid sequence is available but for which the requirements for valid publication of a name according to the Code are not met. The following information should be included in the description of a Candidatus taxon: (a) Genomic information, i.e., nucleic acid sequences apt to determine the phylogenetic position of the organism. (b) All information so far available on structure and morphology (appropriate illustration), physiology and metabolism, reproductive features, the natural environment, in which the organism can be identified by in situ hybridization or similar techniques for cell detection and identification, and any other available and suitable information. A name of an organism in the status of Candidatus consists of the word Candidatus, followed by a name, based on one of the ranks defined in this Code (species, genus, family, etc.), formed in accordance with the nomenclature rules of the Code and its etymology appendix (Appendix 9); see also [113]. Examples: Candidatus Methanoflorentaceae (family rank), Candidatus Methanoflorens (genus rank), Candidatus Methanoflorens stordalenmirensis (species rank). Note that the word Candidatus, but not the name that follows, is printed in italics. Before the implementation of Section 10, Rules 66-73 of the Code, Candidatus names had no pro-standing in prokaryote nomenclature; they 149 Candidatus taxa under Rules of the ICNP and to grant nomenclatural priority to Candidatus names [122, 123] was rejected by the ICSP in 2020 [124]. Murray and Stackebrandt [120] proposed compiling a list of Candidatus taxa based on requests for inclusion submitted by the authors describing them. Starting 2020, lists of proposed Candidatus taxa have been published periodically in the IJSEM as a service to the scientific community [125–128]. Rather than a listing of a ‘codified record’ of each Candidatus taxon (as suggested in [120]), these lists, compiled by the IJSEM List Editors, include the etymologies and references to the publications in which the names were proposed. If necessary, names were corrected, based on the rules of the Code and its Appendix 9 [125,127,128]. Those corrections are proposals only, and alternative corrected names are possible. The Candidatus lists published in the IJSEM are not to be considered as ‘Approved Lists of Names’ that may serve as Validation Lists if, in the future, the ICSP may decide to include Candidatus taxa under the Rules of the Code. At the time of publication of the first two Candidatus lists in the IJSEM, the rank of phylum was not included in the Code, and, therefore, names of Candidatus phyla were not listed. As the ICSP has voted to include the rank of phylum in the Code [5], the List Editors of the IJSEM intend to prepare also an initial list of Candidatus phyla. Authors and other individuals wishing to have new names of Candidatus taxa included still have no standing . A proposal to include names of Candidatus taxa under Rules of the ICNP as validly published names to Candidatus names [113, 114] was rejected by the ICSP in 2020 [115]. Starting 1 January 2025, the new rules to regulate nomenclature of Candidatus names are implemented. In 2020, the ICSP rejected a proposal to recognise Candidatus taxon names as validly published under the ICNP Rules [114, 115]. However, in 2024, the ICSP approved a proposal to grant Candidatus names pro-standing in prokaryotic nomenclature. The new rules (Rules 66 to 73) that formally regulate these names are set out in Section 10 of the Code, which came into effect on 1 January 2025. Please note, however, that Candidatus names still have no standing. Murray and Stackebrandt [112] proposed compiling a list of Candidatus taxa based on requests for inclusion submitted by the authors describing them. Starting 2020, lists of proposed Candidatus taxa have been published periodically in the IJSEM as a service to the scientific community [116–121]. Rather than a 'codified record' of each Candidatus taxon being proposed (as suggested in [112]), these lists, compiled by the IJSEM List Editors, include etymologies and references to publications in which names were proposed. If necessary, the editors corrected the spelling of names based on the rules of the Code and its Appendix 9. These corrections were initially treated as proposals only, with alternative corrected names possible. Candidatus lists no. 1–4 were not originally considered to be a kind of 'Approved Lists of Names' that could serve a similar purpose to Validation Lists. When the first two lists of Candidatus names were published in the IJSEM, the Code did not include the rank of phylum, so names of Candidatus phyla were not listed. However, as the ICSP has since included the rank of phylum in the Code, the List Editors of the IJSEM have prepared an initial list of Candidatus phyla ('Candidatus List No. 5') [120]. 150 in future lists should send an electronic copy of the published paper to the IJSEM List Editors. When an organism of the status Candidatus is later isolated and the pure culture sufficiently described, the name can be submitted for validation according to the Rules of the Code. The former Candidatus name is then deleted from the Candidatus list. The addition of Section 10 (Rules 66 – 73) to the ICNP allows Candidatus names to be pro-validly published. Retroactively, inclusion in Candidatus Lists 1–5 has been deemed sufficient for such names to be pro-validly published [Rule 68(2)]. This, in conjunction with Rule 66(5), also approves the spelling corrections made in Candidatus Lists 1–5. According to Rules 58 and 66(5), cases in doubt should be referred to the Judicial Commission. Candidatus List no. 6 [122] was the first Candidatus List published after the approval of Section 10. Authors and other individuals wishing to have new Candidatus taxon names included in future lists should send an electronic copy of the published paper, along with the relevant documentation, to the IJSEM editorial office. When an organism of the status Candidatus is later isolated and the pure culture sufficiently described, the name can be submitted for validation according to the Rules of the Code. The former Candidatus name is then deleted from the Candidatus list. APPENDIX 12. THE VAN NIEL INTERNATIONAL PRIZE APPENDIX 12. THE VAN NIEL INTERNATIONAL PRIZE The van Niel International Prize, established in 1986 by Professor V. B. D. Skerman of The University of Queensland, honours the contribution of scholarship in the field of microbiology by Professor Cornelis Bernardus van Niel. A history of the prize and a list of recipients from 1986 until 2014 is presented in Appendix 12 of the 2008 Revision of the ICNP [1]. 2014–2017 (Not Awarded) The van Niel International Prize, established in 1986 by Professor V. B. D. Skerman of The University of Queensland, honours the contribution of scholarship in the field of microbiology by Professor Cornelis Bernardus van Niel. A history of the prize and a list of recipients from 1986 until 2014 is presented in Appendix 12 of the 2008 Revision of the ICNP [26]. The prize was not awarded for 2014-2017. 151 2017 – 2020 van Niel Prize recipient , Tanja Woyke The Senate of The University of Queensland, on the recommendation of the Executive Board of the International Committee on Systematics of Prokaryotes, is pleased to present the van Niel International Prize for Studies in Bacterial Systematics for the triennium 2017–2020 to Dr Tanja Woyke in recognition of her contributions made to the field of bacterial systematics [129]. 2017 – 2020 van Niel Prize recipient, Tanja Woyke The Senate of The University of Queensland, on the recommendation of the Executive Board of the International Committee on Systematics of Prokaryotes, is pleased to present the van Niel International Prize for Studies in Bacterial Systematics for the triennium 2017–2020 to Dr Tanja Woyke in recognition of her contributions made to the field of bacterial systematics [123]. 2021–2024 van Niel Prize recipient, [TO BE UPDATED WHEN RELEVANT] The Senate of The University of Queensland, on the recommendation of the Executive Board of the International Committee on Systematics of Prokaryotes, is pleased to present the van Niel International Prize for Studies in Bacterial Systematics for the triennium 2021–2024 to xxxxx APPENDIX 13. ACTIV ITIES OF THE CONGRESSES APPENDIX 13. ACTIVITIES OF THE CONGRESSES T he minutes of the meetings of the International Congress for Microbiology (and later, the International Congress of Bacteriology and Applied Microbiology) of the International Union of Microbiological Societies contain a detailed history of the evolution of this code of nomenclature. A summary of this historical material is presented in Appendix 13 of the 2008 Revision of the ICNP [1]. Minutes of the ICSP plenary meetings held since 2014 are published in the IJSEM and are summarized below. Seventh Congress of European Microbiologists Valencia, Spain, 2017 Meetings of the ICSP were held in July 2017 in conjunction with the seventh Congress of European Microbiologists [130]. The minutes of the meetings of the International Congress for Microbiology (and later, the International Congress of Bacteriology and Applied Microbiology) of the International Union of Microbiological Societies contain a detailed history of the evolution of this code of nomenclature. A summary of this historical material is presented in Appendix 13 of the 2008 Revision of the ICNP [3]. Minutes of the ICSP plenary meetings held between 2014 and 2019 are summarized in Appendix 13 of the 2022 Revision of the ICNP [1]. A plenary meeting of ICSP was held on 22 October 2024 in conjunction with the 18th Congress of the International Union of Microbiological Societies (IUMS) held in Florence, Italy [124]. 152 Reports were received from the Officers of the ICSP and from the JC. A preprint version of the International Code of Nomenclature of Prokaryotes was noted to have been published online. A new publishing contract between the Microbiology Society and IUMS/ICSP has been signed. Negotiations have been ongoing between the authors of the new revision of the Code and the Microbiology Society about the typesetting and the format in which the typeset version will be published be published in the IJSEM. A revision of the ICSP Statutes, proposed by the EB, was approved. The major changes are in Article 2(a) (Term of full members); Article 4 (Term of officers); Article 7 (Secretaries serving as ex officio voting members of the EB); Article 10 (Change of the JC quorum of votes for a favourable decision regarding an Opinion); and Article 13(b) (Clarification of the functions of the Editorial Board of the IJSEM regarding the Code). Reports were received from ad hoc working groups on (1) the nomenclature of uncultured organisms; (2) improving the IJSEM; (3) the position of the ICSP on the Nagoya protocol; (4) education and outreach initiatives on systematics; (5) the organization and structure of the ICSP. Eighth Congress of European Microbiologists Glasgow, Scotland, UK, 2019 A mini-plenary open meeting of the ICSP was held on 11 July 2019 in conjunction with the eighth Congress of European Microbiologists, in Glasgow, Scotland [131]]. The meeting was attended by 13 ICSP members or their alternates and four guests. The revised version of the statutes of the ICSP, as detailed in Whitman et al., Int J Syst Evol Microbiol 2019;69:584–593, were approved by electronic vote of the ICSP in June 2019 and so were noted to now be effective. Reports were presented by the working groups on education and outreach and about the impact of the Nagoya protocol on the availability of type 153 material. The status of the lists of Candidatus names, the preparation of which is in an advanced stage, was discussed. Discussions were held about the proposal to allow gene sequences as type material. These discussions will be continued in future meetings of the ICSP. References 1. Parker CT, Tindall BJ, Garrity GM. International Code of Nomenclature of Prokaryotes (2008 revision). Int J Syst Evol Microbiol 2019;69:S1–S111. 2. Oren A, Arahal DR, Rosselló-Móra R, Sutcliffe IR, Moore ERB. Preparing a revision of the International Code of Nomenclature of Prokaryotes. Int J Syst Evol Microbiol 2021;71:004598. 3. Whitman WB, Bull CT, Busse H-J, Fournier P-E, Oren A, et al. Request for revision of the Statutes of the International Committee on Systematics of Prokaryotes. Int J Syst Evol Microbiol 2019;69:584–593. 4. Oren A, Arahal DR, Rosselló-Móra R, Sutcliffe IC, Moore EJB. Public discussion on a proposed revision of the International Code of Nomenclature of Prokaryotes. Int J Syst Evol Microbiol 2022;71:004918. 5. Oren A, Arahal DR, Rosselló-Móra R, Sutcliffe IC, Moore EJB. Emendation of Rules 5b, 8, 15, and 22 of the International Code of Nomenclature of Prokaryotes to include the rank of phylum. Int J Syst Evol Microbiol 2021;71:004851. 6. Oren A, Arahal DR, Rosselló-Móra R, Sutcliffe IR, Moore ERB. Emendation of general consideration 5 and rules 18a, 24a, and 30 of the International Code of Nomenclature of Prokaryotes to resolve the status of the Cyanobacteria in the prokaryotic nomenclature. Int J Syst Evol Microbiol 2021;71:004939. 7. Turland NJ, Wiersema JH, Barrie FR, Greuter W, Hawksworth DL, et al. (eds). International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code) adopted by the Nineteenth International Botanical References [numbers are provisional] 1. Oren A, Arahal DR, Göker M, Moore ERB, Rossello-Mora R, et al. International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2022 Revision). Int J Syst Evol Microbiol 2023;73:005585. 2. Oren A, Arahal DR, Christensen H, Göker M, Manaia CM, et al. Preparing the 2025 revision of the International Code of Nomenclature of Prokaryotes. Int J Syst Evol Microbiol 2025;75:006666. 3. Whitman WB, Bull C, Busse H-J, Fournier P-E, Oren A, et al. Request for revision of the Statutes of the International Committee on Systematics of Prokaryotes. Int J Syst Evol Microbiol 2019;69:584–593. 4. Arahal DR, Göker M, Hahnke RL, Manaia CM, Moore ERB, et al. Statutes of the International Committee on Systematics of Prokaryotes – July 2025 revision. Int J Syst Evol Microbiol 2025;75:xxx IN PRESS 5. Arahal DR, Bull CT, Busse H-J, Christensen H, Chuvochina M, et al. Guidelines for interpreting the International Code of Nomenclature of Prokaryotes and for preparing a Request for an Opinion. Int J Syst Evol Microbiol 2023;73:005782. 6. Ash C, Priest FG, Collins MD. Paenibacillus gen. nov. In Validation of the Publication of New Names and New Combinations Previously