Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species

519 Neotropical Ichthyology, 7(4):519-568, 2009 Copyright © 2009 Sociedade Brasileira de Ictiologia Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species Andrea de Carvalho Paixão and Mônica Toledo-Piza The taxonomic revision of the genus Lamontichthys Miranda-Ribeiro, based on the examination of 164 specimens of different river drainages throughout the Amazon basin, revealed the presence of six species of which two are new. Lamontichthys filamentosus occurs in the upper and middle portions of the rio Amazonas basin; L. llanero in the río Orinoco basin; L. maracaibero in the lago Maracaibo basin; and L. stibaros in the upper río Amazonas basin. Lamontichthys avacanoeiro, new species, occurs in the upper rio Tocantins basin; and L. parakana, new species, in the lower rio Tocantins basin. The new species represent a considerable extension in the so far known distribution of the genus. A parsimony analysis, including 87 osteological and external morphological characters from Lamontichthys and related taxa (total of 16), resulted in three most parsimonious trees with 194 steps (CI = 0.73 and RI = 0.78). The hypothesis of monophyly of Lamontichthys is corroborated and supported by six derived characters. Within Lamontichthys two monophyletic assemblages are recognized, one includes L. avacanoeiro and L. stibaros, the other includes L. maracaibero and the clade formed by L. filamentosus and L. llanero. The relationships of Lamontichthys parakana, a species that was not included in the phylogenetic analysis is discussed. The monophyly and relationships of the monotypic genus Pterosturisoma microps are also discussed. A revisão taxonômica do gênero Lamontichthys, realizada com base no exame de 164 exemplares de diversas drenagens da bacia amazônica, revelou a existência de seis espécies, das quais duas são novas. Lamontichthys filamentosus ocorre na bacia do alto e médio rio Amazonas; L. llanero, na bacia do rio Orinoco; L. maracaibero, na bacia do lago Maracaibo; e L. stibaros, na bacia do alto rio Amazonas. Lamontichthys avacanoeiro, espécie nova, ocorre na bacia do alto rio Tocantins e L. parakana, espécie nova, na bacia do baixo rio Tocantins. As novas espécies representam uma considerável ampliação da distribuição geográfica do gênero. Uma análise de parcimônia, incluindo 87 caracteres osteológicos e de morfologia externa de 16 táxons, incluindo Lamontichthys e grupos relacionados, resultou em três cladogramas mais parcimoniosos com 194 passos (CI = 0.73 and RI = 0.78). A hipótese de monofiletismo de Lamontichthys é corroborada e sustentada por seis sinapomorfias. Entre as espécies de Lamontichthys, dois grupos monofiléticos são reconhecidos, um incluindo L. avacanoeiro e L. stibaros e outro L. maracaibero e um clado formado por L. filamentosus e L. llanero. A relação de Lamontichthys parakana com as demais espécies do gênero é discutida, apesar da espécie não ter sido incluída na análise filogenética. O monofiletismo e as relações do gênero monotípico Pterosturisoma microps são também discutidos. Key words: Loricariinae, Armored catfish, Taxonomy, Neotropical freshwater, Phylogeny. Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo. Caixa Postal 11461, 05422-970 São Paulo, SP, Brazil. [email protected] (ACP), [email protected] (MTP) Introduction Species of armored catfishes of the genus Lamontichthys Miranda-Ribeiro, comprise small to medium fishes, reaching approximately 20 cm in standard length, and occur in the northern and central regions of South America in the rio Solimões-Amazonas, rio Tocantins, and río Orinoco river basins and in the lago Maracaibo drainage. They inhabit the bottom of rapid flowing streams, but currently very little is known about the biology of the species of Lamontichthys in their natural habitats (Taphorn & Lilyestrom, 1984). As most other catfishes, they have the body completely covered with dermal plates, a ventral sucker-like mouth and jaws provided with very small teeth that are used to scrape the substrate. In addition to having the dorsal and ventral most principal caudal-fin rays elongated, a common feature among loricariids, a few species of Lamontichthys possess the pectoral-fin spine and/or the dorsal-fin spine prolonged into a filament that may far exceed the body length, and large specimens sometimes possess a well developed hunch, dorsally on the head. Among loricariids, Lamontichthys is currently included in the subfamily Loricariinae Bonaparte, whose members are traditionally recognized externally by the possession of a depressed caudal peduncle, the first unbranched principal Systematics of Lamontichthys with the description of new species 520 caudal-fin rays generally prolonged into a long filament, and by the absence of an adipose fin (Reis et al., 2006; Covain & Fisch-Muller, 2007). The Loricariinae currently comprises 34 genera and approximately 200 species (de Pinna, 1998; Ferraris Jr., 2003, 2007) and the subfamily has been considered monophyletic based on various synapomorphies (Schaefer, 1987; Montoya-Burgos et al., 1998). Armbruster (2004) recently discussed the hypotheses of relationships of the Loricariinae within the Loricariidae. Within the subfamily, Lamontichthys has been traditionally grouped together with the genera Cteniloricaria Isbrücker & Nijssen, Harttiella Boeseman, Harttia Steindachner, Pterosturisoma Isbrücker & Nijssen, Sturisoma and Sturisomatichthys Isbrücker & Nijssen (Boeseman, 1971; Isbrücker, 1978, 1980). A recent study focused on the systematics of the Loricariinae was carried out by Rapp Py-Daniel (1997). The taxonomic history of Lamontichthys is relatively recent and the genus currently includes five nominal species, four of which are considered as valid (Ferraris Jr., 2003, 2007). The genus was first proposed by Miranda-Ribeiro (1939: 12) to include Harttia filamentosa LaMonte, from the rio Juruá, a tributary of the right margin of rio Solimões. Subsequently, Boeseman (1971: 6) considered Lamontichthys a junior synonym of Parasturisoma Miranda-Ribeiro. Isbrücker & Nijssen (1978b) examined the holotype of the type-species of Parasturisoma (Loricaria brevirostris Eigenmann & Eigenmann) and concluded that it is a member of the genus Sturisoma Swainson. The authors also diagnosed Lamontichthys based on the presence of seven branched pectoral-fin rays (vs. six in the remaining genera of the Loricariinae; Isbrücker & Nijssen, 1976), described L. stibaros, based on two specimens from Ecuador, and redescribed Lamontichthys filamentosus (LaMonte). Harttia filamentissima Eigenmann & Allen was provisionally considered by Isbrücker & Nijssen (1978b) as a junior synonym of Lamontichthys filamentosus. Although those authors observed variation in a few meristic and morphometric characters of L. filamentosus, the small number of specimens available for study at that time (only 15), precluded a more detailed evaluation of the meaning of such variation. More recently, Taphorn & Lilyestrom (1984) described two new species of Lamontichthys, L. maracaibero and L. llanero, from the lago Maracaibo drainage and the río Orinoco basin respectively, extending considerably the known distribution of the genus to the north and increasing to four the number of valid species in the genus. No additional taxonomic studies of Lamontichthys were carried out subsequently to that of Taphorn & Lilyestrom (1984). Recently, examination of material deposited in various collections revealed that species of Lamontichthys are more widely distributed than previously recorded and in addition there are two additional undescribed species in the genus. Current knowledge about the species level taxonomy and hypotheses of phylogenetic relationships of Lamontichthys derived from the studies mentioned above provide an appropriate framework for a more detailed study focusing on the systematics of Lamontichthys. The main objectives of the present study are to: 1) describe two new species of Lamontichthys and provide new diagnosis for all valid species; 2) update information about the geographic distribution of the recognized species; 3) evaluate the hypothesis of monophyly of Lamontichthys; 4) propose a hypothesis of phylogenetic relationships among the species of Lamontichthys. Material and Methods Species accounts. The taxonomic section of this study was based on the analysis of meristic and morphometric characters, color pattern, and external morphological features, of 164 specimens of Lamontichthys. Counts and measurements were made on the left side of specimens, except when the structure being measured or counted was recognizably abnormal or damaged, in which case corresponding data were taken from the right side. Measurements were taken point to point with digital calipers. Counts were done with the help of a stereomicroscope. Counts and measurements follow Boeseman (1971, 1976), Isbrücker & Nijssen (1978a) and Taphorn & Lilyestrom (1984) with some modifications and with the inclusion of additional data as follows: dentary length: from the lateral to the medial tips of the dentary; caudal-peduncle depth: measured at the vertical through the anterior border of the last dorsal plate; length of branched dorsal-fin ray: measured from base to tip of first branched dorsal-fin ray; length of branched pectoral-fin ray: measured from base to tip of first branched pectoral-fin ray; caudal peduncle depth: measured at the anterior border of the penultimate postdorsal plate, which corresponds to the narrower point of the caudal peduncle. Counts of body plates follow Schaefer (1997) and Reis & Pereira (2000) except as follows: lateroventral thoracic plates: number of plates between the last pectoral-fin ray and the unbranched pelvic-fin ray, and only those in contact with the lateral plates of the mid-ventral series; ventral thoracic plates: number of plates in the largest oblique row located between the contralateral series of lateroventral thoracic plates (Fig. 1). According to Reis & Pereira (2000: 1030), counts of coalescing plates refer to the number of plates in the midventral series in which the two keels are very close. In Lamontichthys, these two keels are not very evident, but through examination of cleared and stained specimens it was observed that the point in which the two keels meet is always coincident with the last plate of the mid-ventral series. In the specimens in alcohol, although the three series of lateral plates are not easily visualized, it is possible to distinguish the last plate of the mid-ventral series paired with the lateral plate of the median series. These two plates possess canals of the lateral sensory system. The last plate of the median series is triangular and situated on the base of the caudal-fin. Roman numerals designate unbranched rays; uppercase roman numerals designate fin-spines. Lamontichthys filamentosus possesses the dorsal and pectoral-fin spines A. de C. Paixão & M. Toledo-Piza 521 and L. llanero the dorsal-fin spine prolonged into long filaments that are often damaged. Therefore, in order to compare variation in dorsal and pectoral-fin lengths of all Lamontichthys species we chose to take this measurement from the base to the tip of the first branched fin ray. The terms “tooth” and “odontods” follow Ørvig (1977), who considers tooth as dental units which are situated on the jaws and pharyngeal plates and odontods are dental units which occupy positions anywhere else in the dermal skeleton. Dentition terminology follows Schaefer (1987) and Müller & Weber (1992). Meristic and morphometric characters were summarized using the program SYSTAT 10.0. Samples from proximate localities were first compared and grouped in one larger sample when no differences were detected. This was done successively until all samples were included in the analysis. Counts and measurements are presented in tables. Subunits of the head are given as proportions of head length (HL). Head length and measurements of body subunits are given as proportions of standard length (SL). In the “Material examined” section of each species account, lots are grouped by country and within each country, by state or department, followed by institutional abbreviation, catalog number, number of specimens in the lot, number of cleared and stained (cs) specimens when present, their range of standard lengths, and specific locality data. Institutional abbreviations follow Leviton et al. (1985) and Leviton & Gibbs (1988) except for Universidade Federal do Rio de Janeiro, Rio de Janeiro (UFRJ). Formal descriptions are provided only for the new species. Redescriptions of Lamontichthys filamentosus, L. llanero, L. maracaibero, and L. stibaros are not presented since their original descriptions or more recent redescriptions provide information to unambiguously diagnose each species (LaMonte, 1935; Isbrücker & Nijssen, 1978b; Taphorn & Lilyestrom, 1984). For these species we provide a synonymy list; diagnosis, geographical distribution, general remarks, and a list of examined material. Osteological characters were not included in the species diagnoses due to the lack of cleared and stained specimens of all species for comparison. Phylogenetic procedures. The phylogenetic study of Lamontichthys was based on the examination of 87 morphological characters, both osteological and from external morphology, in 16 taxa that include five species of Lamontichthys and representatives of nine genera of the Loricariinae proposed as more closely related to Lamontichthys (Boeseman, 1971; Isbrücker, 1978, 1980; Rapp Py-Daniel, 1997) plus one species of Hypostomus and one of Neoplecostomus. Rapp Py-Daniel’s (1997) unpublished study comprises the most recent and detailed cladistic analysis of the Loricariinae and provided the basis for selection of taxa and characters for the phylogenetic analysis carried out in the present study. For this reason and with the consent of the author, in the “Description of characters” section, Rapp Py-Daniel (1997), is credited for all characters or character states that were originally proposed in that study. Many characters were redefined after examination and reinterpretation of data available in the literature, and others were proposed for this just time in the present study. Specimens for osteological study were cleared and counterstained for cartilage and bone using a modification of the method outlined by Taylor & Van Dyke (1985). Cleared and stained specimens were dissected under a stereomicroscope using ophthalmologic instruments. Drawings were made by the first author with the aid of a camera lucida connected to a stereomicroscope. Unless noted in the figure legend, illustrations in lateral view are always oriented with the anterior side to the left, regardless of the side of the specimen used to prepare the illustration, and those in dorsal or ventralview with anterior side to top. Osteological terminology follows Lundberg & Baskin (1969) and Schaefer (1987). Vertebral counts follow Schaefer (1997: 27), in considering each of the five vertebrae of the “Weberian apparatus” all fused in loricariids, and the vertebra that is incorporated in the hypural plate, as separate elements. Precaudal vertebrae refer to those anterior to the vertebra articulated with the first anal-fin pterygiophore, and caudal vertebrae are those posterior to the latter vertebra. One of the new species diagnosed in this study, Lamontichthys parakana, was not included in the phylogenetic analysis due to the reduced number of specimens available which did not allow the preparation of cleared and stained material for the examination of osteological characters. For this species only the external Fig. 1. Ventral view of head and anterior portion of body of Lamontichthys filamentosus (INPA 17927, 79.4 mm SL). Odontods, plates on upper lip and papillae on lower lip not represented. Scale bar = 4 mm. Systematics of Lamontichthys with the description of new species 522 characters are presented in the text. The monophyly of Lamontichthys and the phylogenetic relationships among its species were inferred using the cladistic methodology first proposed by Hennig (1950, 1966) and subsequently discussed by various authors. Detailed explanations about the principles of the cladistic method and its operational aspects are available in Nelson & Platnick (1981), Wiley (1981), Wiley et al. (1991), Swofford et al. (1996) and Amorim (2002). Parsimony analysis was employed to generate hypothesis of phylogenetic relationships and character state transformations using NONA (Goloboff, 1999) associated with Winclada ver. 1.00.08 (Nixon, 2002). The heuristic search was performed with 1000 replications (mult*1000), keeping five trees in each replication (hold/5), and a multiple tree bisectionreconnection (TBR) + TBR search strategy. The cladograms were rooted on Neoplecostomus ribeirensis. The most parsimonious hypotheses generated by the analysis were summarized in a strict consensus cladogram. No specific optimization method, i.e. accelerated transformation optimization (ACCTRAN), or delayed transformation optimization (DELTRAN) was used to optimize characters on the resulting cladograms (i.e. in the list of synapomorphies, ambiguous characters are listed separately from the unambiguous characters). This study is focused on the evaluation of the monophyly of Lamontichthys and the phylogenetic relationships among its species. Characters pertaining to the question of phylogenetic relationships among other genera of the Loricariinae were included with the objective of providing a framework on which to study the relationships within Lamontichthys. Therefore, the scheme of relationships among outgroups that resulted from the present analysis should not be regarded as an attempt to propose a hypothesis of relationships among these taxa. In order to do that, we would have to survey a much larger number of characters and taxa. Discussion of character optimization, polarity and proposed synapomorphies are only provided for the portion of the cladogram pertinent to the question of monophyly of Lamontichthys and intrageneric relationships. Multistate characters that showed a sequence of similarity among their states were treated as ordered (or “minimally connected” - Slowinski, 1993), and includes characters 3, 4, 8, 14, 15, 19, 28, 30, 40, 41, 48, 50, 51, 55, 59, 66, 69, 70, 75, 76, 79, 82, and 85. The initial point of this sequence is represented by state “0”. Multistate characters that did not show any apparent sequence of similarity were treated as unordered (or “maximally connected” - Slowinski, 1993) and includes characters 7,10, 13, 16, 21, 23, 25, 34, 35, 39, 52, 53, 63, 65, 67, 71, 72, 77, 80, 83, and 84. Species listed below followed by an asterisk (*) provided the morphological basis for the phylogenetic analysis of Lamontichthys and are organized alphabetically by genus. The remaining species were examined as comparative material. Whenever a character is mentioned in the text for an outgroup genus without a species cited, it refers to the species listed below, and does not imply that the character is present in all species of the genus. Cleared and stained specimens are indicated by “cs” and those in alcohol are indicated by “alc”. Species name is followed by institutional catalog number, number of specimens in the lot, their range of standard lengths and specific locality data. Comparative taxa: Brazil: Acestridium discus: MZUSP 88944, 1cs, 66.1, 7alc, 34.1-64.9, Amazonas, Rio Preto da Eva, rio Preto da Eva; Farlowella nattereri*: MZUSP 57658, 1cs, 112.9, Amazonas, rio Madeira; Harttia: H. carvalhoi: MZUSP 48598, 1cs, 62.6, 5alc, 69.6-76.6, São Paulo, Pindamonhangaba, tributary of Ribeirão Grande; H. kronei: MZUSP 62390, 1cs, 59.9, São Paulo, Ribeira, Iporanga, rio Betari; H. leiopleura: MZUSP 42701, 2cs, 52.7-58.6, Minas Gerais, Nova Lima, rio das Velhas, tributary of rio Mutuca, paratypes; H. loricariformis*: MZUSP 66187, 1cs, 67.7, Minas Gerais, Muriaé, rio Glória; H. punctata*: MZUSP 40825, 1cs, 68.0, Tocantins, upper Tocantins, rio Bezerra; MNRJ 12726, 1cs, 59.8, 19 (of 120) alc, Goiás, upper Tocantins, córrego Bateias; Harttia sp.: MZUSP 100919, 1cs, 58.8, 2alc, São Paulo, Tietê, Perus, córrego Laranjeiras; H. torrenticola: MZUSP 37170, 1cs, 54.4, Minas Gerais, rio das Velhas, tributary of rio Paraopeba, paratype; Hypostomus sp.*: MZUSP 100921, 1cs, 58.7, 1alc, no locality data; Loricaria sp.*: MZUSP 23847, 1cs, 124.2, Pará, igarapé Açu, near São Domingos do Capim; Neoplecostomus ribeirensis*: MZUSP 100920, 1cs, 45.3, 1alc, São Paulo, Ribeirão das Laranjeiras; Pseudoloricaria punctata*: MZUSP 34542, 1cs, Roraima, rio Branco, Cachoeira do Bem-querer; Pterosturisoma microps*: MZUSP 79909, 1cs, 75.9, Amazonas, rio Solimões below rio Iça; Rineloricaria sp.*: MZUSP 23748, 1cs, 91.5, 16alc, Pará, Oriximiná; Sturisoma sp.*: MZUSP 50112, 1cs, 115.2, Acre, rio Purus. Colombia: Sturisomatichthys leightoni*: ANSP 84179, 1cs, 101.3, 2alc, rio Magdalena basin, Honda. Results Taxonomic account. In the present study six species of Lamontichthys are recognized, two of which are new and recorded from the rio Tocantins basin. Lamontichthys parakana, new species is represented only by three specimens, and L. avacanoeiro, new species is recognized on the basis of 22 specimens. Lamontichthys P. de Miranda Ribeiro Lamontichthys P. de Miranda Ribeiro, 1939: 12 [type-species: Harttia filamentosa LaMonte, 1935, by original designation and monotypy]. Diagnosis. Species of Lamontichthys can be distinguished from all other loricariids by the presence of seven branched rays in the pectoral-fin (vs. six). Harttia leiopleura Oyakawa and Rineloricaria daraha Rapp Py-Daniel & Fichberg also possess seven branched pectoral-fin rays. Species of Lamontichthys can be distinguished from Harttia leiopleura by the presence of dermal plates on the upper lip and lateroventral plates on the thoracic region (vs. absent; Oyakawa, 1993) and from Rineloricaria daraha by having button-like papillae on the ventral surface on the lower lip (vs. long digitiform papillae), the lack of a postorbital notch and A. de C. Paixão & M. Toledo-Piza 523 by having 14 caudal-fin rays (vs. 12; Rapp Py Daniel & Fichberg, 2008). Five other characters observed only in skeletal preparations and detailed under “Character analysis and description” further distinguish Lamontichthys from other loricariids: 1) the trapezoidal shape of the lower pharyngeal plate, with the medial and lateral borders almost parallel, the medial border larger than the posterior border and at least twice as large as the lateral border (character 13); 2) the triangular and relatively elongate posterior expansion of the first epibranchial (character 14); 3) the large coronoid process in the dentary (character 23); 4) the contact (or proximity) between the proximal portions of the first three anal-fin pterygiophores (character 69); 5) the presence of two broad apophysis on the second preural centrum (character 77). Common names. The common names used for Lamontichthys usually refer to more than one species of the genus or even to other Loricariinae. Brazil: “bode-cachoeira”, “bode-cachimbo” and “bode-casco-de-anta” (Silvano et al., 2001; Cunha & Almeida, 2002); Colombia: “bomba” (Galvis et al., 1997); Ecuador: “raspabalsa” (Ferraris Jr., 2003: 336); Finland: “siimaeva” (Varjo et al., 2004); Germany: “filament-störwels” (Baensch & Riehl, 1997); Peru: “shitari” (Ortega & Vari, 1986); Venezuela: “tabla” or “paleta” (F. Provenzano, pers. comm.), and “paleta gibosa” (Taphorn & Lilyestrom, 1984b). Geographic distribution. South American drainages including the upper and central portions of rio Solimões-Amazonas, the drainages of río Ucayali, río Marañon and río Napo, the upper regions of rio Purus and rio Juruá, rio Madeira and rio Tocantins basins. It also occurs in the middle and upper río Orinoco basin, and in the lago Maracaibo drainage (Fig. 2). Key to the species of Lamontichthys 1. Teeth with short cusps (Fig. 3b); anterior tip of snout covered with plates or with an inconspicuous area lacking plates; dentary 11.5-19.1% HL in specimens larger than 100 mm SL .............................................................................. 2 1’. Teeth with long cusps (Fig. 3a); anterior tip of snout not covered with plates (Fig. 4); dentary 18.4-23.4% HL in specimens larger than 100 mm SL ....................................... 4 Fig. 2. Map of central and northern portions of South America showing geographic distribution of the species of Lamontichthys (numbers indicate type localities): 1. L. avacanoeiro (lozenge), 2. L. filamentosus (triangle), 3. L. llanero (rudder), 4. L. maracaibero (open squares), 5. L. parakana (number 5), and 6. L. stibaros (solid squares). Some symbols represent more than one locality or lot of specimens. Fig. 3. Lateral view, distal portion to top, of left premaxillary tooth of Lamontichthys avacanoeiro (MZUSP 61974, 113.7 mm SL, paratype) (a), and L. filamentosus (LACM 41741-9, 119.4 mm SL) (b). Detail of cusps in anterior view, distal tip to left. Scale bar = 0.5 mm. Fig. 4. Dorsal view of head of Lamontichthys stibaros (FMNH 84111, 62.4 mm SL). Location of mesethmoid represented by a dotted line on median portion of snout. Arrow points to portion of snout not covered with plates. Scale bar = 1 mm. Systematics of Lamontichthys with the description of new species 524 2. 19-21 lateral plates in the mid-ventral series; a single large triangular plate extending from base of last pelvic-fin ray to anterior margin of anus (Fig. 5); 5-6 lateroventral thoracic plates in specimens larger than 100 mm SL; dorsal-fin spine not prolonged into a long filament. (lago Maracaibo drainage) ........................................................ L. maracaibero 2’. 15-18 lateral plates in the mid-ventral series; more than one plate from base of last pelvic-fin ray to anterior margin of anus (Fig. 1); 6-10 lateroventral thoracic plates in specimens larger than 100 mm SL (Fig. 1); dorsal-fin spine prolonged into a long filament ............................................ 3 5. First branched dorsal-fin ray 26.1-36.8% SL and pectoralfin spine 22.9-30.5% SL in specimens larger than 50 mm SL; dark pigments scattered along dorsal-fin spine. (tributaries of upper rio Amazonas) ....................................... L. stibaros 5’. First branched dorsal-fin ray 21.9-26.0% SL and pectoralfin spine 19.7-22.4% SL in specimens larger than 50 mm SL; dark pigments arranged in transversal bands along dorsalfin spine. (upper rio Tocantins basin) ........ L. avacanoeiro Fig. 5. Ventral view of pelvic region of Lamontichthys maracaibero (MCNG 3592, 154.9 mm SL). Arrow points to single plate from base of last pelvic fin-ray to margin of anus. Fig. 6. Schematic drawing of dorsal view of head of Lamontichthys llanero (a) and L. filamentosus (b). The “x” indicates interorbital distance and “y” indicates distance from orbit to exposed border of cleithrum. 3. Pectoral-fin spine prolonged into a long filament in specimens larger than 60 mm SL; head width 97.4-111.1% HL; interorbital distance equal to distance from orbit to exposed margin of cleithrum (rarely shorter) (Fig. 6). (upper and middle rio Amazonas basin) ............................................. L. filamentosus 3’. Pectoral-fin spine not prolonged into a long filament; head width 82.6-96.9% HL; interorbital distance larger than (rarely equal to) distance from orbit to exposed margin of cleithrum (Fig. 6). (rio Orinoco basin) .................... L. llanero 4. Distal tip of last dorsal-fin ray extending short of vertical through anal-fin origin; orbital diameter 16.6-17.3% HL in specimens larger than 70 mm SL; two small plates on the ventral mid-line of the caudal peduncle (Fig. 7). (rio Tocantins basin) ................................................ L. parakana 4’. Distal tip of last dorsal-fin ray at the vertical through analfin origin; orbital diameter 13.6-16.8% HL in specimens larger than 70 mm SL; three small plates on the ventral midline of the caudal peduncle (Fig. 7) ..................................... 5 Fig. 7. Ventral view of distal tip of caudal peduncle of Lamontichthys parakana (INPA 3010, 112.7 mm SL, holotype) (a) and L. avacanoeiro (MZUSP 79750, 96.8 mm SL, paratype) (b). The asterisks indicate plates on the ventral mid-line of the caudal peduncle. Scale bar = 1 mm. A. de C. Paixão & M. Toledo-Piza 525 Lamontichthys avacanoeiro, new species Fig. 8 Holotype. MNRJ 32795, 150.5 mm SL, Brazil, Goiás, rio Tocantins, pools below U.H.E. Serra da Mesa, 1996, D. F. Moraes et al. Paratypes. (22 specimens; 47.6-159.9 mm SL). Brazil. Goiás: MNRJ 18553, 1 cs, 7 alc, 76.0-145.6, same data of holotype; MZUSP 54090, 2, 47.6-58.4, rio Tocantinzinho and tributaries, Serra da Mesa, 48°21’66”S 13°53’33”W, 28 Out 1996, Expedition MZUSP/MNRJ; MZUSP 61974, 5, 1cs*, 113.7-159.9, upper rio Tocantins, Minaçu, Serra da Mesa, 26 Out 1996, A. Akama & O. T. Oyakawa; MZUSP 79750, 5, 90.9-96.8, upper rio Tocantins, Uruaçu, rio Passa Três, above Ponte Nova, on road BR 153, 10 Jun 1998, D. F. Moraes. Non-types. (4 specimens; 83.4-106.8 mm SL): Brazil: Goiás: MNRJ 23641, 1, 100.3, upper rio Tocantins, rio das Almas; MNRJ 23642, 1, 106.8, upper rio Tocantins, rio Bagagem, above ferry-boat to Garimpinho; MNRJ 23643, 2, 83.4-83.7, upper rio Tocantins, Niquelândia, rio Traíras, above Indianópolis. Diagnosis. Lamontichthys avacanoeiro differs from all congeners in the shorter first branched dorsal-fin ray (22.626.0%, vs. 26.4-40.5% SL) in specimens larger than 70 mm SL. Lamontichthys avacanoeiro can be further distinguished from L. filamentosus, L. llanero, and L. maracaibero by the anterior tip of the snout with an oval shaped area without plates (vs. tip of snout totally covered with plates or, with only a very small area lacking plates), and by the teeth with long cusps (vs. short) (Fig. 3). Lamontichthys avacanoeiro can be further distinguished from L. filamentosus and L. llanero by the lower lip semi-oval shaped (vs. semicircular) (Fig. 9). Lamontichthys avacanoeiro also differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior margin of the anus Fig. 8. Lamontichthys avacanoeiro, new species, MNRJ 32795, 150.5 mm SL, holotype. Dorsal, lateral and ventral views. Systematics of Lamontichthys with the description of new species 526 (vs. one plate) (Figs. 1 and 5) and in the greater abdominal length in specimens larger than 150 mm SL (17.6-17.7% [n = 2], vs. 14.1-16.3% SL [n = 5]). Lamontichthys avacanoeiro can be distinguished from L. parakana by the more posterior location of the anal-fin origin (at the vertical through the distal tip of the last dorsal-fin ray, vs. anterior to that point), by the shorter unbranched anal-fin ray (16.9-20.3%, vs. 21.4-24.8% SL), and by the smaller orbital diameter (13.6-16.2%, vs. 16.617.3% HL) in specimens larger than 70 mm SL. Lamontichthys avacanoeiro also differs from specimens of L. parakana larger than 100 mm SL in the narrower head (91.3-100.9%, vs. 101.3-106.1% HL). Description. Morphometric and meristic data presented in Table 1. Largest specimen 159.9 mm SL. Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly to caudal-fin base and, anteriorly, to snout tip. Head ellipse shaped in dorsal view. Dorsal profile of head slightly convex. Dorsal profile of body straight from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of longest anal fin ray, straight from that point to caudal-fin base. Largest body width at cleithrum, gradually narrower posteriorly to 20th to 21st lateral plate of median series, more abruptly posteriorly into caudal-fin base. Caudal peduncle long, narrow and very depressed. Ventral profile of body and head straight from snout tip to base of caudal fin. Pectoral-fin origin at vertical through posterior margin of orbit. Dorsal-fin origin immediately anterior to vertical through pelvic-fin origin. Analfin origin at or slightly posterior to vertical through distal tip of last dorsal-fin ray. Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral, upper and lower lips semi-oval shaped. Lower lip extending short of vertical through anterior margin of orbit and covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower than lower lip, its ventral surface (internal) with small papillae and dorsal surface (external) with small, round plates covered with odontods. Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip. Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader Table 1. Morphometric and meristic data for Lamontichthys avacanoeiro and L. filamentosus. SD = standard deviation. Range of L. avacanoeiro includes paratypes. L. avacanoeiro L. filamentosus Variable Holotype N Range Mean SD N Range Mean SD Standard length (mm) 150.5 24 47.6-159.9 108.1 64 38.8-172.5 134.9 Percents of standard length Head length 20.9 24 19.8-25.3 22.3 1.5 64 16.0-20.2 17.6 0.9 Predorsal length 29.9 24 28.4-33.0 30.5 1.2 64 26.0-30.8 27.7 0.9 Postanal length 49.9 24 47.7-52.7 50.0 1.3 64 51.3-57.3 55.1 1.0 Abdominal lenght 16.9 24 15.2-17.7 16.7 0.7 64 13.6-16.8 15.4 0.6 Thoracic length 16.9 24 13.7-16.9 15.2 0.9 64 13.6-16.7 15.2 0.7 Dorsal-fin length - 21 20.5-26.0 24.1 1.3 57 27.8-39.9 36.0 2.3 Pectoral-fin length 19.3 24 18.2-22.0 20.1 0.8 62 20.5-26.1 23.4 1.3 Pelvic-fin length 17.7 24 17.7-20.6 19.2 0.8 64 18.9-23.0 20.7 1.0 Anal-fin length 17.3 22 16.9-20.3 19.1 1.0 56 19.9-26.9 23.3 1.4 Body depth at dorsal-fin origin 11.8 23 9.3-12.5 10.6 1.1 64 10.2-13.9 12.5 0.8 Caudal peduncle depth 1.5 24 1.3-1.8 1.5 0.1 64 1.4-1.9 1.6 0.1 Body width at dorsal-fin origin 16.6 24 13.5-16.9 15.4 0.9 64 13.8-16.9 15.6 0.7 Body width at anal-fin origin 12.9 23 10.2-13.1 12.0 0.8 64 11.2-14.4 13.1 0.6 Body width at caudal-fin origin 2.7 23 2.4-2.9 2.7 0.2 64 2.5-3.3 2.9 0.2 Percents of head length Head width 97.7 23 85.6-100.9 92.8 3.9 64 96.7-111.1 105.2 3.7 Interorbital distance 27.3 24 25.4-29.4 27.1 1.2 64 28.4-35.2 32.1 1.6 Orbital diameter 13.8 24 13.6-16.2 14.6 0.8 64 10.9-18.4 16.4 1.2 Snout length 62.2 24 60.6-64.8 62.7 1.1 64 55.4-63.3 59.8 1.4 Dentary length 20.8 24 18.4-23.4 20.8 1.5 64 11.5-20.2 14.1 1.4 Lower lip width 14.8 22 13.0-21.2 16.0 2.3 64 7.6-16.7 12.2 1.9 Meristic data Lateral plates of median series 32 23 31-34 32.6 0.8 64 32-34 32.8 0.5 Lateral plates of mid-ventral series 19 24 14-20 17.7 1.5 63 14-18 14.8 0.8 Ventrolateral thoracic plates 7 24 6-9 7.0 0.8 63 5-8 6.9 0.7 Premaxillary teeth 96 21 60-100 82.8 10.7 61 33-78 62.5 8.4 Dentary teeth 83 21 50-87 73.4 9.4 60 30-70 55.1 7.8 Dorsal-fin rays II,7 22 II,7 II,7 0.0 62 II,6-7 I,7 0.1 Pectoral-fin rays I,7 22 I,7 I,7 0.0 64 I,7 I,7 0.0 Pelvic-fin rays i,5 22 i,5 i,5 0.0 64 i,5 i,5 0.0 Anal-fin rays i,5 22 i,5 i,5 0.0 64 i,5 i,5 0.0 Caudal-fin rays i,12,i 22 i,12,i i,12,i 0.0 61 i,12,i i,12,i 0.0 A. de C. Paixão & M. Toledo-Piza 527 than lateral cusp. Number of jaw teeth increasing with growth. Number of premaxillary teeth approximately 8% greater than number of dentary teeth. Emergent teeth placed in two irregularly arranged rows; teeth gradually smaller laterally. Replacement teeth oriented at 90 degrees relative to emergent teeth and covered with skin. Anteroventral tip of snout without plates, forming distinct naked portion, approximately oval shaped, covered with stiff connective tissue. Anterior border of head covered with small and flexible plates between snout tip and anterolateral margin of upper lip. Lateral border of head covered with large dorsal plates anteroventrally curved. Three horizontal keels along trunk, on lateral plates, converging from plate 5 to 15 or 16, continuing as a single keel posteriorly. Lower keel more evident, upper keel less evident. Last lateral plate of median series small and triangular, with one diminutive plate on each side of its base, located between two other plates of similar shape (one upper and other lower), above caudal-fin base. Lateral plates of median series, 31 to 34. Lateroventral thoracic plates 6 to 9 in specimens larger than 50 mm SL. Ventral thoracic plates, small, lozenge shaped, irregularly arranged in oblique rows; longest row with 8 to 10 plates delimited by ventrolateral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge-shaped plates followed by three large polygonal plates, and the anal plate larger and bordering anterior margin of anus. Pectoraland dorsal-fin spines, unbranched pelvicand anal-fin rays not projecting as long filaments. Unbranched caudal-fin rays projecting as long filaments. Branched caudalfin rays gradually longer toward dorsal and ventral unbranched rays. Dorsal most branched caudal-fin ray longer than ventral most ray. Unbranched pelvic-fin ray reaching to vertical through second ventral plate, located posterior to base of last anal-fin ray, unbranched anal-fin ray reaching to vertical through seventh ventral plate, located posterior to the base of last anal-fin ray. Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i. Color in alcohol. Ground coloration of head and body of adults and juveniles varying between brown and yellow. Ventral region of head and body lighter, uniformly yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from base of last anal-fin ray to base of unbranched lower caudal-fin ray. Fins and dorsal region of body and head with dark brown and yellow spots. One dark brown, longitudinal band extending from base of dorsal fin to base of caudal fin. Etymology. The species name, avacanoeiro, is in reference to the Avá-canoeiros, inhabitants from the upper rio Tocantins basin. Avá-canoeiros, an American group that historically inhabited the area of the upper rio Tocantins, drainage from which the examined specimens of the species in this study originated. Geographic distribution. Upper rio Tocantins basin (Fig. 2). Comments. The occurrence of Lamontichthys in the upper rio Tocantins was first reported by Rapp Py-Daniel (pers. comm.), based on specimens collected in the region of Serra da Mesa, State of Goiás, Brazil. Specimens from lots MNRJ 23641 - 23643 are in poor condition, therefore they were not designated as paratypes. Lamontichthys filamentosus (LaMonte, 1935) Fig. 10 Harttia filamentosa LaMonte, 1935: 5-6, fig. 4 [original description; type locality: Brazil, Amazonas, rio Juruá drainage, vicinity of mouth of rio Embira, tributary of the rio Tarauacá, 7°30’S 70°15’W]; Conci & Michelangeli, 1974: 226 [listed]. Lamontichthys filamentosa: Miranda-Ribeiro, 1939: 12 [original description of genus; designation of typespecies]; Gosline, 1945: 108 [listed]; Barzanti & Oldani, 1976: 130-137 [incorrect identification; based on four specimens of probably, Loricaria sp., Loricariinae; Argentina, rio Paraná basin - specimens not examined]. Harttia filamentissima Eigenmann & Allen, 1942: 211, 445, pl. VIII figs. 1 and 2 [original description; type locality: Peru, Loreto, río Huallaga; Fowler, 1945: 109 [listed; Peru]; Gosline, 1945: 108 [listed]; Tovar Serpa, 1967: 222 [listed; Peru]; Ovchynnyk, 1968: 258 [Chicherota, near the mouth of the río Bobonaza, tributary of the upper río Pastaza, specimen not examined]. Lamontichthys filamentosus: Ovchynnyk, 1968: 258 [Eastern Ecuador]; Isbrücker & Nijssen, 1976: 121-122 [7 branched pectoral-fin rays as diagnostic for Lamontichthys; Harttia filamentissima presumed to be a synonym of L. filamentosus]; Isbrücker & Nijssen, 1978b: 57-80, fig. 1-4, 7, 10a,c, 14, table Ia, IIa-h, IIIa [redescription; Harttia filamentissima as synonym of L. filamentosus; photographs of types of both species; specimens not examined]; Isbrücker, 1978: 88 [listed]; Isbrücker, 1980: 91 [listed]; Ortega & Vari 1986: 17 [literature compilation; Peru]; Burgess, 1989: 426-427, 440 [description]; Barriga, 1991: 66 [eastern drainages of Ecuador]; Lauzanne et al., 1991: 70, 73, table I and IV [Bolivia, upper rio Madeira basin, Fig. 9. Ventral view of oral region of Sturisoma sp. (MZUSP 50112, 115.2 mm SL) (a) and Lamontichthys avacanoeiro (MNRJ 18553, 98.1 mm SL, paratype) (b). Scale bar = 2 mm. Systematics of Lamontichthys with the description of new species 534 covered with stiff connective tissue. Anterior border of head with small, flexible plates between snout tip and anterolateral margin of upper lip. Lateral border of head covered with larger dorsal plates anteroventrally curved. Three inconspicuous horizontal keels along body, from plates 6 to 14 or 16. Last plate of median lateral series diminutive and triangular, located on caudal-fin base, between two slightly larger plates of similar shape (one upper and one lower, upper plate slightly larger than lower plate). Lateral plates of median series, 32-33. Small ventral thoracic plates lozenge shaped, arranged in irregular, oblique rows. Longest row with 7 to 8 plates delimited by lateroventral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge shaped plates, followed by one larger plate that form anterior border of anus. Pectoraland dorsal-fin spines, unbranched pelvicand anal-fin rays not projecting into long filaments. Unbranched caudal-fin rays of both specimens damaged, except lower unbranched caudalfin ray from one specimen which projects as long filament. Branched caudal-fin rays gradually longer toward upper and lower unbranched rays. Dorsal most branched caudal-fin ray slightly longer than ventral most ray. Unbranched pelvic-fin ray reaching vertical through anterior border of first ventral plate posterior to base of anal fin. Unbranched anal-fin ray reaching eighth ventral plate posterior to base of anal fin. Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i. Color in alcohol. Coloration of paratype faded, uniform yellow. Color pattern based only on holotype. Ground coloration of head and body brown or yellow. Ventral region of head and body lighter, uniform yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from last anal-fin ray to base of unbranched lower caudal-fin ray. Dorsal region of body with three longitudinal, dark brown bands extending from base of dorsal fin to base of caudal fin. Two of these bands extending ventrally to cover lateral plates. Third band extending along dorsal midline of body, from dorsal-fin base to caudal-fin base. Bands gradually narrower posteriorly. A transversal, dark brown band between bases of pectoral-fins, with anterior margin at posterior tip of supraoccipital. Dorsal portion of head dark brown with slightly lighter areas. All fin rays with dark brown pigmentation. Anterior half of dorsalfin dark brown, remaining of fin hyaline. Paired fins and analfin dark brown. Caudal-fin base and three upper most and L. parakana L. stibaros Variable Holotype Range Mean SD N Range Mean SD Standard length (mm) 112.7 72.2-119.0 101.3 25 27.2-172.8 73.7 Percents of standard length Head length 20.6 20.6-22.4 21.3 1.0 25 18.4-28.5 22.5 2.2 Predorsal length 29.1 29.1-31.1 30.1 1.0 25 23.3-33.7 30.4 2.2 Postanal length 51.6 51.6-60.6 55.3 4.7 25 41.3-62.3 50.9 3.8 Abdominal length 16.8 15.9-17.1 16.6 0.6 25 4.9-17.0 15.0 2.2 Thoracic length 14.7 14.7-16.1 15.4 0.7 25 13.3-17.1 15.4 0.9 Dorsal-fin length 29.9 26.4-31.0 29.1 2.4 24 24.0-36.8 29.4 3.1 Pectoral-fin length 22.4 21.0-22.8 22.0 1.0 25 20.7-25.1 23.0 1.1 Pelvic-fin length 21.5 18.8-22.2 20.8 1.8 25 17.5-22.9 20.1 1.3 Anal-fin length 22.8 21.4-24.8 23.0 1.7 25 17.5-22.9 20.3 1.4 Body depth at dorsal-fin origin 11.6 10.8-12.7 11.7 0.9 25 1.8-12.1 10.2 2.0 Caudal peduncle depth 1.5 1.5-1.8 1.7 0.1 25 1.5-9.8 2.1 1.6 Body width at dorsal-fin origin 15.2 14.1-16.5 15.3 1.2 25 10.2-16.4 14.4 1.3 Body width at anal-fin origin 12.5 11.6-13.2 12.4 0.8 25 7.8-26.2 17.5 5.6 Body width at caudal-fin origin 2.6 2.6-3.1 2.8 0.3 25 2.3-3.1 2.7 0.2 Percents of head length Head width 101.3 95.2-106.1 100.9 5.5 25 73.5-102.2 88.6 6.5 Interorbital distance 26.4 26.4-30.1 27.6 2.1 25 26.4-30.9 28.3 1.2 Orbital diameter 16.6 16.6-17.3 16.9 0.4 25 13.8-27.8 16.6 2.7 Snout length 61.6 59.3-62.5 61.1 1.6 25 52.8-65.8 59.4 2.8 Dentary length 21.7 20.1-22.6 21.5 1.2 25 14.7-24.3 19.9 2.3 Lower lip width 14.0 14.0-18.0 16.0 2.0 25 11.2-18.9 14.5 2.0 Meristic data Lateral plates of median series 32 32-33 32.3 0.6 25 33-35 34.0 0.5 Lateral plates of midventral series 18 18 18 0.0 25 19-20 19.5 0.5 Ventrolateral thoracic plates 6-7 6-7 6.3 0.6 25 0-8 6.3 1.5 Premaxillary teeth 76-88 55-76 64.3 10.7 24 36-109 60.9 16.6 Dentary teeth 64-67 49-67 55.3 10.1 25 34-94 58.6 14.8 Dorsal-fin rays II,7 II,7 II,7 0.0 25 II,7 II,7 0.0 Pectoral-fin rays I,7 I,7 I,7 0.0 25 I,7 I,7 0.0 Pelvic-fin rays i,5 i,5 i,5 0.0 25 i,5 i,5 0.0 Anal-fin rays i,5 i,5 i,5 0.0 25 i,5 i,5 0.0 Caudal-fin rays i,12,i i,12,i i,12,i 0.0 24 i,12,i i,12,i 0.0 Table 3. Morphometric and meristic data for Lamontichthys parakana (n = 3) and L. stibaros. SD = standard deviation. Range of L. parakana includes holotype and paratypes. A. de C. Paixão & M. Toledo-Piza 535 lower most branched rays dark brown. Etymology. The species name, parakana, is in reference to the Parakanã, inhabitants of the margins of the lower rio Tocantins, in the State of Pará. Parakanã, an American group that historically inhabited the area of the lower rio Tocantins, drainage from which the examined specimens of the species in this study originated. Geographic distribution. Known from the type locality at lower rio Tocantins, below Tucuruí Dam (Fig. 2). Lamontichthys stibaros Isbrücker & Nijssen, 1978 Fig. 14 Lamontichthys stibaros Isbrücker & Nijssen, 1978b: 66-69, figs. 8 and 9, 10d, 14, table Ic, Ii-j, IIIb [original description; type locality: Ecuador, “Prov. Pastaza, rio Amazon system, rio Bobonaza in Chicherota, 02°25’S 76°38’W, altitude aprox. 260-280 m, upper rio Pastaza”]; Isbrücker, 1980: 92 [listed]; Ortega & Vari, 1986: 17 [literature compilation; Peru]; Burgess, 1989: 426-427 [listed; description]; Barriga, 1991: 66 [literature compilation; Oriental Ecuador]; Ferraris & Vari, 1992: 27 [type listed]; Eschmeyer, 1998: 1611 [listed]; Isbrücker, 2001: 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Ferraris Jr., 2007: 264 [listed]; Sullivan et al., 2006: [Siluriform higher-level relationships; molecular data, specimen not examined]. Diagnosis. Lamontichthys stibaros differs from all other species of the genus, with the exception of L. avacanoeiro and L. parakana, in the lack of plates on the anterior tip of the snout (vs. anterior portion of snout totally covered with plates or with an inconspicuous naked area), in the teeth with long cusps (vs. short) (Fig. 3), and in the lower lip semi-oval shaped (vs. semicircular) (Fig. 3). Lamontichthys stibaros differs from L. avacanoeiro and L. parakana in the longer first branched dorsal-fin ray (29.736.8%, vs. 22.6-31.0% SL), in specimens larger than 70 mm SL. It further differs from L. avacanoeiro in the longer first branched pectoral-fin ray (21.7-25.1%, vs. 19.2-22.0% SL) and from L. parakana in the narrower head (89.1-101.4%, vs. 101.3106.1% HL). The presence of 19 to 20 lateral plates along the mid-ventral series (vs. 14 to 18) and the longer dentary (18.6-23.2%, vs. 11.517.3% HL) in specimens larger then 70 mm SL also distinguishes L. stibaros from L. filamentosus and L. llanero. Lamontichthys stibaros differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior border of the anus (vs. one plate) (Figs. 1 and 5) and in the uniform color pattern of the fins (vs. with brown and gray spots). Morphometric and meristic data are presented in Table 3. Geographic distribution. Upper rio Amazonas basin (Fig. 2). Lamontichthys stibaros occurs in sympatry with L. filamentous in the drainages of río Santiago, río Marañón and río Ucayali, in Peru. Material examined (25 specimens; 27.2-172.8 mm SL): Peru: Amazonas: LACM 39897-1, 3, 42.2-89.5, río Santiago; LACM 39884-3, 2, 100.2-120.1, Marañón, río Santiago; LACM 39647-1, 1, 172.6, Marañón, río Cenepa, close to río Tujushiku. Ayacucho: ROM 47093, 2, 122.6-150.1, near to confluence between río Mantaro and Tambo Apurimac. Ucayali: FMNH 84137, 7, 27.2-58.2, río San Alejandro; FMNH 84131, 2, 43.8-47.3; FMNH 84112, 3, 63.386.6, río San Alejandro; FMNH 84111, 6, 49.3-100.1, 1 cs*, 62.4, río San Alejandro. Description of characters and phylogenetic analysis Characters and their respective states analyzed in this study are grouped according to the region of the body with which they are associated. Neurocranium 1. Ventral depression at anterior tip of mesethmoid: (0) absent; (1) present (CI = 100; RI = 100). The mesethmoid of loricariids varies considerably in shape but usually its posterior portion is relatively elongate, narrow, and cylindrical. The lateral projections (cornuas) at the anterior tip of the ossification may be extremely reduced or absent (Schaefer, 1990: 175; 1998: 394) and the median anteroventral portion is usually thin and lacks a groove or cavity. Uniquely among taxa examined, the mesethmoid of L. filamentosus, L. llanero, and L. maracaibero possesses an anteroventral depression (Fig. 15a). A strong, anteriorly directed ligament attaches to this groove and is, apparently, connected to plates on the snout tip. 2. Tissue adhered to anterior tip of mesethmoid: (0) present; (1) absent (CI = 50; RI = 0). A thick layer of tissue, strongly adhered to the anterior tip of the mesethmoid, which may be covered by plates, is present in all taxa examined except Farlowella and Pseudoloricaria. This feature was previously described by Rapp Py-Daniel (1997: character 8). 3. Shape of mesethmoid disk: (0) robust, circular in lateral view with margins of disk much broader than central portion; (1) laminar shaped, circular in lateral view; (2) laminar shaped, rectangular to triangular in lateral view, similar to a keel (CI = 66; RI = 83). The ventral surface of the mesethmoid of astroblepids and loricariids possesses a vertical process on the median longitudinal line close to the premaxillae and is referred to as the mesethmo-premaxillary articular condyle or mesthmoid disk (Schaefer, 1987: 5; 1998: 384). Ligaments that sustain the premaxillae are inserted on this process and enable their ample mobility (Schaefer, 1987). In Lamontichthys, Harttia, Hypostomus, Neoplecostomus, Pterosturisoma, and Sturisomatichthys, the mesethmoid disk is robust, circular in lateral view and with the margins of the Systematics of Lamontichthys with the description of new species 536 disk much broader than the central portion (Figs. 15 and 16a). In the two conditions considered as derived, the mesethmoid disk is more delicate (Fig. 16b-c). In Farlowella and Sturisoma, although the disk is also approximately circular in lateral view it is laminar shaped. In Loricaria, Pseudoloricaria, and Rineloricaria, the mesethmoid disk is also laminar shaped, but the lamina is thin and rectangular to triangular in lateral view, similar to a keel. 4. Position of mesethmoid disk relative to anterior mesethmoid margin: (0) terminal, on anterior margin of mesethmoid; (1) subterminal, at short distance from anterior margin of mesethmoid; (2) non-terminal, far from anterior margin of mesethmoid (CI = 50; RI = 33). The position of the mesethmoid disk relative to the anterior mesethmoid margin is variable within the Loricariidae (Schaefer, 1991; 1998: 384; Armbruster, 2004). The Ancistrinae, a few Hypoptopomatinae, Hypostominae, and Neoplecostomus possess the mesethmoid disk located at the terminal anterior margin of the mesethmoid, a condition shared with the Astroblepidae (Fig. 16a, Schaefer, 1987: fig. 3; 1991: 7). Other loricariids possess the mesethmoid disk in a non-terminal Fig. 14. Lamontichthys stibaros, INHS 84111, 100.1 mm SL. Dorsal, lateral and ventral views. A. de C. Paixão & M. Toledo-Piza 537 position, at varying distances from the anterior margin of the bone (Figs. 15 and 16b-c). The distance between the mesethmoid disk and the anterior margin of the mesethmoid is short in Lamontichthys, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, and Rineloricaria, and longer in Farlowella, Sturisoma, and Sturisomatichthys. 5. Anterior portion of vomer: (0) thick, with short anterior prolongations; (1) elongate, with one or two long and narrow prolongations (CI = 50; RI = 83). In Loricariids the vomer is elongate with reduced lateral wings, and is sutured anteriorly to the mesethmoid and posteriorly to the parasphenoid (Schaefer, 1987: 5). The anterior portion varies in shape and the posterior portion is tapered at the end, forming an elongate tip (Rapp Py-Daniel, 1997: character 9). In Lamontichthys, Harttia, Neoplecostomus, and Sturisomatichthys the vomer has a thick anterior portion, with very short anterior prolongations (Fig. 15). In the derived condition, present in Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma the anterior portion of the vomer is elongate, and has one or two long and narrow prolongations (Fig. 16b-c). Schaefer (1987: 5; 1997a: 23) observed a similar condition in Hypostomus plecostomus (Hypostominae) and in Otocinclus (Hypoptopomatinae). 6. Dorsal projection (or lateral wall) on dorsolateral region of lateral ethmoid: (0) extending along entire lateral border of bone; (1) extending approximately from posterior half of lateral border of bone (CI = 33; RI = 60). The lateral ethmoid in loricariids encapsulates the nasal organ from below (Howes, 1983; Schaefer, 1991). Anteriorly, Fig. 15. Ventral view of mesethmoid, lateral ethmoid, anterior portion of vomer, and posterior portion of autopalatine of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a), and L. avacanoeiro (MZUSP 61974, 113.7 mm SL, paratype) (b, left). Lateral view of these structures (b, right). Scale bar = 1 mm. Fig. 16. Lateral (upper) and ventral (lower) views of the mesethmoid of Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (a), Rineloricaria sp. (MZUSP 23748, 91.5 mm SL) (b), and Farlowella nattereri (MZUSP 57658, 112.9 mm SL) (c). Arrow points to the mesethmoid disk, anterior to top. Scale bar = 1 mm. Systematics of Lamontichthys with the description of new species 538 the lateral ethmoid has a concave face, with cartilage, that articulates with the autopalatine. Posteriorly, the lateral (vertical), ventral (horizontal) and medial (vertical) walls of the capsule are open only dorsally. The meeting of these walls shape part of the anterior border of the orbit. In the Callichthyidae (except Aspidoras, Brochis, and Corydoras) and most loricariids, including Neoplecostomus, the lateral wall is formed by the anterior condyle of the lateral ethmoid that completely encapsulates the nasal organ (Howes, 1983: 331; Schaefer, 1998: 394). This condition occurs in Farlowella, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys. In Lamontichthys, Harttia, Pterosturisoma, and Sturisoma the lateral wall of the lateral ethmoid is formed more posteriorly, leaving anteriorly a small portion lacking an ossified wall (Fig. 17; Howes, 1983: 331), a condition shared with the Hypoptopomatinae (Schaefer, 1998: 394). Pterosturisoma microps possesses the dorsal border of the nasal fossa circular, while in the other taxa the border is oval. This condition was not codified in the present analysis, however it may be tentatively proposed as autapomorphic for this species. 7. Type of contact between lateral ethmoid and dorsal border of metapterygoid: (0) through posterior process; (1) through posterior process and anterior short suture; (2) through interdigitating margins, with no process (CI = 66; RI = 66). Among the Siluriformes, only in the family Loricariidae the ventral surface of the lateral ethmoid contacts the dorsal border of the metapterygoid (Schaefer, 1987). In Lamontichthys, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys this contact is limited to the posterior portion of the dorsal border of the metapterygoid, which articulates with the lateral ethmoid by processes present on both ossifications, a condition shared with Neoplecostomus and most loricariids (Fig. 18a). In the derived condition, Farlowella and Hypostomus possess an additional contact characterized by a short suture in the anterior portion of the metapterygoid (Fig. 18c). In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal border of the metapterygoid contacts the lateral ethmoid by an interdigitating type of contact (Fig. 18b). Schaefer (1991: 7; 1998: 394) reported the presence of a vertical lamina in the lateral ethmoid contacting the metapterygoid in various loricariids (Ancistrinae, most Hypoptopomatinae, Hypostominae, most Loricariinae, and Neoplecostomus), however, he did not describe variation in the type of contact between these structures. 8. Lateral process of sphenotic: (0) long; (1) short; (2) inconspicuous or absent (CI = 66; RI = 0). Located lateral to the supraoccipital, the sphenotic forms the dorsoposterior portion of the orbit in the majority of the Loricariidae and bears part of the temporal laterosensory canal (Schaefer, 1987: 6). The sphenotic of loricariids is usually square-shaped with one long lateral process. Schaefer (1987: 6) considered the lateral process of the sphenotic in loricariids as homologous to the prominent “lateral spine” representative of the Siluriformes in general. However, Howes (1983: 95) considered that the lateral spine present in the sphenotic of primitive Teleostei is absent in Siluriformes, including the Diplomystidae (Arratia, 1987: 92), Scoloplacidae (Schaefer, 1990: 180) and the Loricariidae. Astroblepids and many loricariids possess a long lateral process of variable width on the sphenotic (Armbruster, 2004: 26), while other loricariids possess a relatively short and wide or inconspicuous process. Variation in the size of this process is accompanied by several degrees of participation of the sphenotic in the margin of the orbit. Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys possess a long sphenotic process of variable width, a condition shared with other loricariids such as Hypostomus and Neoplecostomus (Fig. 19). In this condition, the sphenotic contributes with 1/5 or more to the dorsoposterior margin of the orbit. Sturisoma possesses a short and wide lateral process, and the sphenotic contributes with approximately 1/5 of the border of the orbit, and in Pterosturisoma this process is much shorter and the sphenotic has little or no contribution to the margin of the orbit (Fig. 20). Observation of this character is better accomplished with Fig. 17. Dorsal (a) and lateral (b) views of the lateral ethmoid of Pterosturisoma microps (MZUSP 79909, 75.9 mm SL). Arrow points to anterior portion of lateral ethmoid that lacks an ossified wall. A. de C. Paixão & M. Toledo-Piza 539 the sphenotic separate from the rest of the neurocranium. 9. Orbital notch in sphenotic: (0) absent; (1) present (CI = 100; RI = 100). The orbital notch is formed by an anteroventral laminar expansion of the sphenotic, in the region where the sphenotic forms the posterior margin of the orbit, and its presence is considered derived within loricariids and proposed as autapomorphic for the tribe Loricariini (Boeseman, 1971: 17). Among examined taxa, the presence of an orbital notch is restricted to the clade that includes members of the Loricariini, Loricaria, Pseudoloricaria, and Rineloricaria (Fig. 19). Fig. 18. Ventral view of region of contact between the lateral ethmoid and dorsal border of metapterygoid of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a), Rineloricaria sp. (MZUSP 23748, 91.5 mm SL) (b) and Farlowella nattereri (MZUSP 57658, 112.9 mm SL) (c). Arrows points to the region of contact between the two ossifications. Scale bar = 1 mm. Fig. 19. Lateral view of left side of bones surrounding orbit of Rineloricaria sp. (MZUSP 23748, 91.5 mm SL). Arrow points to orbital notch. Scale bar = 1 mm. Hyoid Arch and Branchial Arches 10. Relative width of ventral laminar expansion along posterior border of anterior ceratohyal: (0) widens abruptly in lateral portion; (1) widens gradually from medial to lateral portion, narrow; (2) widens gradually from medial to lateral portion, broad (CI = 50; RI = 66). In the Astroblepidae and Loricariidae the anterior and posterior ceratohyals possess a ventral laminar expansion along their posterior borders, forming an angle of approximately 90º with the remaining of the hyoid arch (anterohyal of Schaefer, 1987: 12). Schaefer & Lauder (1986) discussed various specializations in the musculature and osteology of the hyoid arch in the Astroblepidae and Loricariidae associated with the life-style of members of these families. These fishes continue to respire while maintaining the suck pressure of the oral disk (Alexander, 1965: 136). In addition, the ceratohyal of the Loricariidae possesses expansions forming a broad surface for the attachment of the associated musculature (Schaefer & Lauder, 1986: 500). The ventral expansion of the posterior border of the anterior ceratohyal varies among loricariids. In Farlowella, Hypostomus, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys the laminar expansion widens abruptly in the lateral portion of the bone. In Lamontichthys (except L. avacanoeiro), Harttia, and Systematics of Lamontichthys with the description of new species 540 Sturisoma, the ventral expansion of the anterior ceratohyal is relatively narrow overall, and it widens gradually along the extension of the bone (Fig. 21). Although in L. avacanoeiro the ventral expansion of the anterior ceratohyal also widens gradually along the extension of the bone the ossification is relatively broad, distinctly wider than the expansion in the other species of Lamontichthys. 11. Ossification in basibranchial 3: (0) absent; (1) present (CI = 100; RI = 100). The first basibranchial commonly present in the Otophysi is absent in the Siluriformes (Arratia, 1987: 41). The branchial arches of the Loricariidae possess three basibranchials (2, 3 and 4), with basibranchial 2 being ossified, basibranchial 4 cartilaginous, and basibranchial 3 having variable degrees of ossification among taxa (Schaefer, 1987: 12). The Ancistrinae, many Hypoptopomatinae, Hypostominae and Neoplecostomus possess the basibranchial 3 cartilaginous (Schaefer, 1987: 12), a condition herein observed in Hypostomus and Neoplecostomus. The presence of ossification in basibranchial 3 is considered derived within the Loricariidae and occurs in Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys. 12. Shape of first hypobranchial: (0) stick-shaped; (1) fanshaped (CI = 100; RI = 100). Loricariids possess five pairs of hypobranchials, the first pair is ossified and the others cartilaginous (Schaefer, 1987: 12). The first hypobranchial in loricariids is usually stickshaped and slightly wider in the medial tip. However, some loricariids possess a derived condition, wherein the lateral portion of the first hypobranchial is considerably broader than the medial portion resulting in a fan-shaped ossification (Armbruster, 2004: 11). In the present study, a fan shaped first hypobranquial was observed only in Loricaria and Pseudoloricaria. In the other loricariids examined, including Lamontichthys, the first hypobranchial is stick-shaped, gradually widening towards the lateral margin (Fig. 22). 13. Shape of lower pharyngeal plate: (0) stick-shaped, slightly expanded; (1) triangular; (2) approximately rectangular, with posterior border parallel to anterior border, medial and lateral borders of similar length; (3) quadrangular, medial and lateral borders parallel, medial border approximately same length of posterior border and slightly longer than lateral border; (4) trapezoidal, medial and lateral borders almost parallel, medial border larger than the posterior border and at least twice larger than the lateral border (CI = 100; RI = 100). The fifth ceratobranchial in the Otophysi is modified into a plate–like ossification with teeth, and within the Loricariidae there is wide variation in the shape of the pharyngeal plate (Schaefer, 1987: 12). The fifth ceratobranchial in Neoplecostomus is a somewhat broad ossification with a narrow dorsal end, a condition considered plesiomorphic for the Siluriformes (Fig. 23; Arratia, 1987: 41). Armbruster (2004: 9) characterized the shape of the lower pharyngeal plate of most Loricariinae as widened at least anteriorly to form a hatchetlike structure. In the present study, four different conditions may be further distinguished regarding the lower pharyngeal of the Loricariinae. Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys possess the lower Fig. 20. Lateral view of region of snout and orbit (left side) of Pterosturisoma microps (MZUSP 79909, 75.9 mm SL) (a) and Sturisoma sp. (MZUSP 50112, 115.2 mm SL) (b). Arrow points to margin of sphenotic that borders the orbit. Scale bar = 2 mm. Fig. 21. Anterior view of hyoid and branchial arches of Lamontichthys stibaros (FMNH 84111, 62.4 mm SL). Branchial filaments not represented. Scale bar = 2 mm. A. de C. Paixão & M. Toledo-Piza 541 pharyngeal plate approximately triangular and little expanded. In Harttia this structure is also little expanded, however it is somewhat rectangular-shaped, with the posterior border parallel to anterior border and medial and lateral borders of similar length (Fig. 24a). The lower pharyngeal plate is considerably enlarged in Lamontichthys and Sturisoma. In Sturisoma the lower pharyngeal plate is approximately quadrangular, the medial and lateral borders are parallel, and the medial border has approximately the same length of the posterior border and is slightly longer than the lateral border (Fig. 24b). In Lamontichthys, the lower pharyngeal plate is approximately trapezoidal, with the medial border larger than the posterior border and, at least, twice as large as the lateral border (Fig. 25a). 14. Posterior expansion of first epibranchial: (0) absent; (1) triangular, short; (2) triangular, relatively elongate (CI = 40; RI = 66). The posterior border of the first epibranchial in Lamontichthys has a long triangular laminar expansion that is projected medially (Fig. 26a). In the other Loricariinae examined, this projection is absent or relatively short. Farlowella, Harttia, Loricaria, and Rineloricaria do not possess any projection in the posterior border of this bone (Fig. 26c), and Pseudoloricaria, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a short laminar projection (Fig. 26b). Schaefer (1987: 12) described the presence of a posterior process in the first epibranchial for Hypostomus plecostomus, and the condition of this species was coded as 1 in the present study. 15. Uncinate process at posterior border of third epibranchial: (0) absent; (1) short; (2) long (CI = 50; RI = 66). The third epibranchial in the majority of the Loricariidae possesses an uncinate process with varying degrees of development (Rapp Py-Daniel, 1997: character 75). When present, the process arises from the posteromedial border of the epibranchial, and extends into the medial portion of the brachial arches. A small dorsolateral process is present in the third epibranchial of Hypostomus plecostomus (Schaefer, 1987: 14) and Harttia loricariformis (Fig. 27). The third epibranchial in Lamontichthys, Farlowella, Harttia punctata, Neoplecostomus, Pterosturisoma, Fig. 22. Dorsal view of hypobranchial 1 and basibranchials 2 and 3 of Lamontichthys avacanoeiro (MZUSP 61974, 113.7 mm SL, paratype) (a), and Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (b). Scale bar = 0.5 mm. Fig. 23. Ventral view of the lower pharyngeal plate of Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL). Scale bar = 0.5 mm. Fig. 24. Ventral view of the lower pharyngeal plate of Harttia loricariformis (MZUSP 66187, 67.7 mm SL) (a) and Sturisoma sp. (MZUSP 50112, 115.2 mm SL) (b). Scale bar = 1 mm. Systematics of Lamontichthys with the description of new species 542 Sturisoma, and Sturisomatichthys possesses a relatively long process extending meso-posteriorly (Fig. 27), and Loricaria, Pseudoloricaria, and Rineloricaria lack such a process on the third epibranchial. Fig. 25. Dorsal view of posterior portion of branchial arches of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a) and Sturisoma sp. (MZUSP 50112, 115.2 mm SL) (b). Cartilages not represented. Scale bar = 1 mm. Fig. 26. Dorsal view of first epibranchial (right side) of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a), Pterosturisoma microps (MZUSP 79909, 75.9 mm SL) (b), and Harttia loricariformis (MZUSP 66187, 67.7 mm SL) (c). Arrow points to posterior process of first epibranchial. Scale bar = 1 mm. Fig. 27. Dorsal view of third epibranchial of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (right side) (a) and Harttia loricariformis (MZUSP 66187, 67.7 mm SL) (left side) (b). Arrow points to posterior process of third epibranchial. Scale bar = 0.5 mm. 16. Shape of upper pharyngeal tooth plate: (0) drop-shaped, anterior portion slightly narrower than posterior; (1) half-moon shaped to triangular, anterior portion much narrower; (2) circular to quadrangular, convex; (3) laminar and triangular shaped, with a fold on the posterior margin (CI = 100; RI = 100). The Siluriformes possess a single pair of upper pharyngeal plates, connected to the fourth pharyngobranchial (Fink & Fink, 1981: 323). Teeth arranged in various patterns on the upper pharyngeal plate make contact with the dorsal surface of the fifth ceratobranchial, or lower pharyngeal plate. The upper pharyngeal plate of Lamontichthys, Harttia, Pterosturisoma, and Sturisomatichthys possess a robust ventral surface and a dorsal laminar projection (Fig. 28a). Teeth are located on the ventral surface, which is triangular shaped with a narrow anterior portion. The upper pharyngeal plate of Neoplecostomus and other loricariids, such as Acestridium discus, lacks a dorsal laminar projection and the ventral surface is drop-shaped with a slightly narrow anterior portion, and completely covered by teeth (Figs. 23 and 28c). The upper pharyngeal plate of Sturisoma is laminar and triangular shaped, and differs considerably from other examined taxa in having the teeth in a small folded area on the posterior border of the plate and along the medial border (Fig. 25b). This condition is proposed as autapomorphic for Sturisoma. The ventral surface, which usually has teeth in other taxa, is covered by branchial filaments, while the dorsal surface is smooth. Loricaria, Pseudoloricaria, and Rineloricaria possess a relatively large pharyngeal plate, slightly convex, circular to quadrangular shaped with teeth distributed on the entire ventral face (Fig. 28b). Schaefer (1991: 12; 1998: 396) described the general condition of the upper pharyngeal plates in the Loricariidae, as plane, relatively large and wedge-shaped. Members of the A. de C. Paixão & M. Toledo-Piza 543 Hypoptopomatinae (Otothyris, Pseudotothyris, and Schizolecis) alternatively have a small, compact and rounded upper pharyngeal tooth plate. Armbruster (2004: 12) described two distintict conditions of this plate in the Loricariidae. In the present study four different conditions regarding the shape of the upper pharyngeal plate among examined specimens of Loricariidae were observed. 17. Molariform teeth on upper and lower pharyngeal plate: (0) absent; (1) present (uninformative). Loricariids commonly possess only conical teeth on the upper and lower pharyngeal plates. However, many members of the Loricariini possess both conical and molariform teeth in both plates (Rapp Py-Daniel 1997: character 90; Armbruster, 2004: 9), a condition observed in Loricaria among examined taxa. Jaws and dentition The Loricariidae surpasses all other Loricarioidea in the high diversity of shapes and sizes of jaws and teeth, probably a consequence of the adaptation to different kinds of microhabitats and substrates explored by these fishes. Associated with the variation of jaws and teeth, there are several other specializations in the feeding mechanisms and in the hyoid apparatus (Schaefer & Lauder, 1986: 504). 18. Length of posterior process of palatine: (0) short, not extending beyond anterior condyle of lateral ethmoid; (1) long, extending beyond anterior condyle of lateral ethmoid (CI = 50; RI = 0). The palatine in loricariids is narrow and cylindrical. Anteriorly there is a cartilaginous tip that articulates with the maxilla and posteriorly there is an articular surface for the lateral ethmoid (Arratia, 1990: 209). Medial to this latter articular surface is a ventral posterior process, extremely reduced in loricariids in comparison to other Siluriformes (Fig. 15a; Schaefer, 1987: 10; Schaefer, 1997: 25; Reis, 1998: 124). Lamontichthys avacanoeiro and Loricaria, in contrast, possess a long posterior process compared to other loricariids (Fig. 15b). In these two species, the posterior process of the palatine extends ventrally beyond the anterior condyle of the lateral ethmoid. In other loricariids, the posterior process fails to reach the condyle of the lateral ethmoid. According to Schaefer (1990: 185), in loricariids, one of the two subdivisions of the extensor tentaculi muscle inserts on the posterior process of the palatine. 19. Lateral flange of palatine: (0) absent; (1) present and incomplete; (2) present and complete (CI = 66; RI = 66). In loricariids, the palatine is usually a cylindrical bone lacking lateral edges (Schaefer, 1997: fig. 12e; Armbruster, 2004: 17). In a few taxa there is a flange projecting from the lateral border of the bone that is already present early in ontogeny (Arratia, 1990: 209). In many members of the Loricariini the flange extends along the entire lateral margin of the autopalatine, a condition observed in Pseudoloricaria and Rineloricaria. In Loricaria, exclusively, the flange is somewhat shorter extending along 2/3 of the lateral margin of the autopalatine (Rapp Py-Daniel, 1997: character 23). 20. Palatine splint: (0) present; (1) absent (CI = 50; RI = 50). The palatine splint is an ossification of questionable homology that occurs in the Astroblepidae, Scoloplacidae, Loricariidae, some Trichomycteridae and Callichthyidae (Schaefer, 1987: 10; 1997: 25; Reis, 1998: 124). In loricariids the ossification is thin, elongate and straight with a wide anterior tip, and contacts the anterior cartilage of the autopalatine (Fig. 29). Posteriorly, it extends parallel to the autopalatine, and reaches the lateral ethmoid. The palatal splint is present in all examined taxa except Farlowella, Loricaria, and Pseudoloricaria. 21. Length of cup-shaped portion of premaxilla relative to Fig. 28. Ventral view of upper pharyngeal plate (left side) of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a), Rineloricaria sp. (MZUSP 23748, 91.5 mm SL) (b) and Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (c). Scale bar = 0.5 mm. Systematics of Lamontichthys with the description of new species 550 39. Flange on lateral region of seventh precaudal vertebra: (0) absent; (1) present, anteriorly directed; (2) present, posteriorly directed (CI= 100; RI = 100). Members of the subfamily Loricariinae have a flange projecting from the dorsolateral side of the seventh precaudal vertebra that extends dorsally along the side of the neural spine. In all examined members of the Loricariinae except Lamontichthys avacanoeiro, the flange is directed anteriorly (Fig. 38a). In L. avacanoeiro, this flange is directed posteriorly. Members of the Loricariidae in general seem to lack a lateral flange on the seventh precaudal vertebra (Fig. 38b). 40. Hemal spine on last precaudal vertebra: (0) absent; (1) present, shorter or same length of associated vertebral centrum; (2) present, longer than associated vertebral centrum (uninformative). Pterosturisoma possesses the hemal spine of the last precaudal vertebra considerably elongate and narrow distally, with a length of approximately twice that of the corresponding vertebral centrum (Fig. 39). In Neoplecostomus and in the great majority of the Loricariinae (Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys) this spine is considerably shorter, its length equal or less than the length of the corresponding vertebral centrum (Figs. 40 and 41). 41. Bifid hemal spine on first caudal vertebra: (0) very short, almost inconspicuous; (1) medium, length approximately 1/2 width of corresponding vertebra; (2) long, approximately, as long as corresponding vertebra (CI = 100; RI = 100). In Hypostomus, the hemal spine of the first caudal vertebra is very short and only its distal posterior tip is split to receive the first anal-fin pterygiophore. The bifid hemal spine of the first caudal vertebra in Neoplecostomus is longer, its length approximately 1/2 of the corresponding vertebral width (Fig. 41). In members of the Loricariinae there is a further elongation Fig. 36. Lateral view of region of snout and orbit (left side) of Lamontichthys avacanoeiro (MNRJ 18553, 98.1 mm SL, paratype). Arrow points to plate between infraorbitals 2 and 3. Scale bar = 2 mm. Fig. 37. Ventral view of posterior portion of neurocranium and anterior portion of Weberian apparatus of Rineloricaria sp. (MZUSP 23748, 91.5 mm SL). Bones were disarticulated to allow better visualization of features mentioned in the text. Scale bar = 2 mm. Fig. 38. Lateral view of sixth, seventh and eighth vertebra and predorsal plates (right side) of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL) (a, scale bar = 2 mm), and Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (b, scale bar = 1 mm). A. de C. Paixão & M. Toledo-Piza 551 of this structure and in Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys, the bifid hemal spine of the first caudal vertebra is as long as the corresponding vertebral width (Fig. 40).In Pterosturisoma two very long contralateral projections originate from the proximal region of the hemal spine (Fig. 39). It is not clear whether these processess are homologous to the bifid hemal spines or represent distinct structures (Rapp PyDaniel, 1997: 64) and this species was therefore coded as “?”. 42. Presence of completely expanded, hemal spines on caudal vertebrae: (0) from first caudal vertebra; (1) from fifth, sixth or seventh caudal vertebra (uninformative). Neoplecostomus and members of the Loricariinae possess completely expanded hemal spines ranging from the fifth, sixth or seventh caudal vertebrae (vertebrae 20 to 23), to the last body vertebra (Figs. 39-41). According to Schaefer (1987: 17), in Hypostomus plecostomus the hemal spines are completely expanded along their length in all caudal vertebrae (posterior to vertebrae 14), a condition observed in the specimens of Hypostomus examined in the present study. 43. Bilateral projections on vertebrae: (0) absent; (1) present (CI = 100; RI = 100). Members of the Loricariinae possess ventrally directed Fig. 39. Lateral view of the portion of the axial skeleton associated with the anal-fin pterygiophores (right side) of Pterosturisoma microps (MZUSP 79909, 75.9 mm SL). Dorsal-fin pterygiophores not represented. Scale bar = 2 mm. Fig. 40. Lateral view of the portion of the axial skeleton associated with the dorsal and anal-fin pterygiophores (right side) of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL). Scale bar = 3 mm. Systematics of Lamontichthys with the description of new species 552 bilateral projections on the proximal portion of the hemal spines, as well as dorsally directed bilateral projections on the proximal portion of the neural spines, a feature previously described by Rapp Py-Daniel (1997: 106) as a synapomorphy for Loricariinae. These projections are strong and narrow, their length not exceeding one third of the vertebral width (Figs. 39 and 40). The two anterior most pairs of these projections usually do not contact the body plates, while the more posterior ones possess the distal tips firmly sutured to these plates. The dorsally directed bilateral projections are present from vertebrae 9 to 11, and the ventrally directed bilateral projections, from approximately vertebrae 13 to 15. 44. Orientation of ventrally directed bilateral projections on second caudal vertebra: (0) ventral to slightly anteriorly or posteriorly directed; (1) distinctly posteriorly directed; (2) distinctly anteriorly directed (CI = 66; RI = 66). The ventrally directed bilateral projections of the second caudal vertebra of the majority of the Loricariinae are directed ventrally or only slightly anterior or posterior and their distal tips lack any type of contact with the body plates. In Harttia the ventrally directed bilateral projections of the second caudal vertebra are directed posteriorly and their distal tips also lack any type of contact with the body plates (Fig. 42a). Lamontichthys llanero has the ventrally directed bilateral projections of the second caudal vertebra anteriorly directed and the distal tips are strongly sutured to the hemal spine of the first caudal vertebra (Fig. 42b). This character does not apply to Hypostomus and Neoplecostomus because these taxa lack ventrally directed bilateral projections. 45. Contact between ventrally directed bilateral projections of third caudal vertebra and ventral plates of body: (0) absent; (1) present (uninformative). The ventrally directed bilateral projections of the third caudal vertebra of the majority of Loricariinae (except Harttia loricariformis) possess their distal tips pointed and lacking any type of contact with the ventral plates (Fig. 39). In Harttia loricariformis, the distal tips of these projections are strongly Fig. 41. Lateral view of the portion of the axial skeleton associated with the anal-fin pterygiophores (right side) of Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL). Dorsal-fin pterygiophores and anal-fin rays not represented. Scale bar = 3 mm. Fig. 42. Lateral view of part of the axial skeleton (right side) of Harttia loricariformis (MZUSP 66187, 67.7 mm SL) (a), and Lamontichthys llanero (INHS 29957, 105.2 mm SL) (b). Arrow points to distal portion of the parahemal spine of second caudal vertebra. Scale bar = 1 mm. A. de C. Paixão & M. Toledo-Piza 553 attached to the ventral plates of the body (Fig. 42a). Hypostomus and Neoplecostomus were not coded for this character due to lack of bilateral projections on the vertebrae of these taxa. 46. Length of posterior process of hemal spine of second preural centrum: (0) long; (1) short (CI = 100; RI = 100). The hemal spine of the second preural centrum in all examined taxa extends posteriorly as a process along the ventral margin of the hypural plate (Fig. 43). In all members of the Loricariinae this process is short not extending beyond half the length of the hypural plate. Alternatively, in Hypostomus and Neoplecostomus this process is long almost reaching the vertical through the posterior margin of the hypural plate. 47. Cartilage on posterior tip of hemal spine of second preural centrum: (0) present; (1) absent (CI = 100; RI = 100). Harttia, Hypostomus, and Neoplecostomus among examined taxa possess cartilage on the posterior tip of the hemal spine of the second preural centrum. This feature was previously reported in members of the Astroblepidae, Ancistrinae, Hypoptopomatinae, Hypostominae, and Neoplecostominae, and in Harttia among the Loricariinae by Rapp-Py Daniel (1997: character 135). 48. Relative length of neural spine of second preural centrum: (0) reaches vertical through posterodorsal tip of hypural plate; (1) reaches vertical through 1/2 to 3/4 length of hypural plate; (2) reaches vertical through 1/3 length of hypural plate (CI = 100; RI = 100). Three different conditions of the relative length of the neural spine of the second preural centrum were described by Rapp Py-Daniel (1997: character 134) for the Loricariidae. Among examined taxa, Hypostomus possess an elongate neural spine of the second preural centrum that extends parallel to the dorsal border of the hypural plate to the vertical through its posterodorsal tip (Fig. 43c). In all other examined taxa the neural spine of the second preural centrum is shorter. In Lamontichthys, Harttia, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the neural spine of the second preural centrum reaches the vertical through 1/2 to 3/4 length of the hypural plate (Fig. 43). In Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria the neural spine of the second preural centrum reaches the vertical through 1/3 the length of the hypural plate. 49. Caudal peduncle depth: (0) cylindrical or moderately depressed; (1) depressed (CI = 100; RI = 100). According to Alexander (1965: 142), one of the main modifications along the evolution of the Siluriformes was the depression of the body in adaptation to a bottom-feeding habit. One extreme of this modification occurs in the Loricariidae, whose members have the ventral surface of the body very flat. In addition, the caudal peduncle of loricariids is slightly depressed, though still cylindrical in overall shape. The Fig. 43. Lateral view of second preural centhrum and caudalfin skeleton (right side) of Harttia loricariformis (MZUSP 66187, 67.7 mm SL) (a, scale bar = 0.5 mm), Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (b, scale bar = 0.5 mm), and Hypostomus sp. (MZUSP 100921, 58.7 mm SL) (c scale bar = 1 mm). Detail of each illustration show dorsal view of hypurapophysis. Systematics of Lamontichthys with the description of new species 554 subfamily Loricariinae and the genera Acestridium, Niobichthys, and Oxyropsis (Hypoptopomatinae) possess the caudal peduncle extremely depressed. Schaefer (1987: 20) hypothesized a depressed caudal peduncle to be a synapomorphy for the subfamily Loricariinae. This feature has been used to diagnose the Loricariinae since the original recognition of this taxon (Bonaparte, 1831; Eigenmann & Eigenmann, 1890). 50. Number of precaudal vertebrae: (0) 14 or more; (1) 13; (2) 12; (3) 11 (CI = 100; RI = 100). The Loricariidae possess 26 to 42 vertebrae between the basioccipital and the hypural plate (Schaefer, 1987: 24; 1990: 190; 1997: 105). The increase in the total number of vertebrae is derived within loricariids (Schaefer, 1987: 24), with the greatest number present in the subfamily Loricariinae, with 33-37 vertebrae (vs. 30 or fewer). The Astroblepidae and Callichthyidae possess 16-18 precaudal vertebrae and the Loricariidae 12-16 (Hypostominae and Ancistrinae with 1316; Hypoptopomatinae and Loricariinae with 12) (Schaefer, 1987: 24). Within the Loricariinae there is a secondary reduction in the number of precaudal vertebrae. Lamontichthys and Harttia possess 13 precaudal vertebrae, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma possess 12 precaudal vertebrae, and Sturisomatichthys has 11 precaudal vertebrae (Rapp PyDaniel, 1997: character 110). 51. Number of caudal vertebrae: (0) 23-25; (1) 19-22; (2) 12-18 (CI = 50; RI = 75). Among examined taxa Hypostomus and Neoplecostomus possess 12 to 18 caudal vertebrae and all members of the Loricariinae possess 19 or more. Harttia, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys possess 19 to 22 caudal vertebrae and Lamontichthys, Farlowella, Pterosturisoma, and Sturisoma possess 23 to 25 caudal vertebrae (Rapp Py-Daniel, 1997: character 111). Dorsal-fin 52. Spinelet: (0) shaped as strong and short spine, articulated with first pterygiophore; (1) shaped as small plate; (2) absent (CI = 50; RI = 33). The majority of the Siluriformes possess the first element of the dorsal-fin (often termed the spinelet, Schaefer, 1987: 17) shaped as a strong, short, and spine-like element that acts as a locking system for the second much longer dorsal-fin spine (Alexander, 1965), a condition observed in Hypostomus, among examined taxa. The spinelet is variably reduced or lost in several memberos of the Loricariidae (Schaefer, 1987: 18; Armbruster, 2004: 33). In Lamontichthys (including L. parakana), Harttia punctata, Neoplecostomus, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the spinelet is shaped as a plate-like structure (Fig. 44), and Farlowella, Harttia loricariformis, Loricaria, and Pseudoloricaria lack the spinelet. 53. Type of articulation between proximal portion of dorsalfin spine and second dorsal-fin pterygiophore: (0) through condyle on dorsal region of pterygiophore; (1) through simple contact with pterygiophore, with no condyle; (2) via chainlink structure (CI = 66; RI = 50). The second element of the dorsal-fin in the Siluriformes is usually modified into a defensive spine (Reed, 1924), and the proximal end of this spine articulates with a dorsal condyle of the second pterygiophore (Fig. 45a; Schaefer, 1987: 23), a condition observed in Hypostomus, among examined taxa. In Lamontichthys, Farlowella, Harttia punctata, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the dorsal-fin spine articulates with the second pterygiophore via a chain-like structure (Fig. 45b), a condition proposed as synapomorphic for the Loricariinae by Schaefer (1987: 23) and posteriorly corroborated by Armbruster (2004: 33). In Harttia loricariformis and Neoplecostomus the dorsal surface of the second pterygiophore is flat, lacking any structure for articulation. The dorsal-fin pterygiophores of the majority of loricariids possess transverse processes, which provide support for the dermal body plates. Usually, the processes of the anterior most pterygiophores are long, and decrease in size posteriorly (Schaefer, 1991: 18). The number of dorsal-fin pterygiophores Fig. 44. Dorsolateral view of the dorsal-fin of Lamontichthys stibaros (FMNH 84111, 62.4 mm SL). Cartilages not represented. Scale bar = 1 mm. A. de C. Paixão & M. Toledo-Piza 555 bearing transverse processes varies within the Loricariidae (Armbruster, 2004: 33). Variations pertaining to the dorsal-fin pterygiophores observed in the present study are discussed under characters 54 to 59. 54. Length of transverse process of first dorsal-fin pterygiophore relative to second dorsal-fin pterygiophore: (0) shorter; (1) of similar length (uninformative). The first and the second dorsal-fin pterygiophores of loricariids possess a pair of relatively long transverse processes, involved in the support of the nuchal plate and first rays of the dorsal-fin (Schaefer, 1991: 18). In Neoplecostomus these processes are of similar length, and in the other loricariid examined, the lateral processes of the first dorsal-fin pterygiophore are shorter than those of the second. This character was previously described by Rapp-Py Daniel (1997: character 120). 55. Orientation of transverse process of second dorsal-fin pterygiophore: (0) lateral at proximal portion and anterolateral at distal portion; (1) anterolateral throughout entire extension; (2) anterolateral at proximal portion and anterior at distal portion (CI = 66; RI = 83). Different types of orientation of the lateral process of the second dorsal-fin pterygiophore were described for the Loricariidae by Rapp Py-Daniel (1997: character 118). The condition in which the lateral process of the second dorsalfin pterygiophore is directed anterolaterally along its entire extension occurs in Lamontichthys, Pterosturisoma, Sturisoma, and Sturisomatichthys (Fig. 46a). The lateral process of the second dorsal-fin pterygiophore directed anterolaterally at its proximal portion and anteriorly at its distal portion occurs in Loricaria, Pseudoloricaria, and Rineloricaria (Fig. 46b). The lateral process of second dorsalfin pterygiophore directed lateral at its proximal portion and anterolateral at its distal portion occurs in Farlowella, Harttia, Hypostomus, and Neoplecostomus (Fig. 46c). 56. Contact between transverse process of third and fourth dorsal-fin pterygiophores and dorsal body plates: (0) present; (1) absent (uninformative). In the majority of the loricariids examined (with the exception of Neoplecostomus) the lateral processes of the third and fourth dorsal-fin pterygiophores are long and contact the ventral surface of the dorsal body plates (Fig. 44). According to Schaefer (1991: 18) Neoplecostomus lacks transverse processess on the third and fourth pterygiophores, however, two very short processes are present in the specimen of N. ribeirensis examined in the present study and they fail to reach the dorsal plates. 57. Transverse process on fifth dorsal-fin pterygiophore: (0) absent; (1) present (CI = 50; RI = 50). The majority of the Loricariinae examined possess a transverse process on the fifth dorsal-fin pterygiophore (Fig. 44). Sturisomatichthys lacks these processes, a condition that also occurs in Hypostomus and Neoplecostomus. 58. Transverse process of sixth dorsal-fin pterygiophore: (0) absent; (1) present (CI = 50; RI = 75). Harttia, Hypostomus, Neoplecostomus, and Sturisomatichthys lack a transverse process on the sixth dorsal-fin pterygiophore. Small transverse processes are present in Lamontichthys, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma (Fig. 44). 59. Connecting bone: (0) present, contacting first or second dorsal-fin pterygiophore; (1) present, not contacting any pterygiophore; (2) absent (CI = 50; RI = 50). The connecting bone or lateral bone (Bailey & Baskin, 1976; Schaefer, 1987: 26) is a laminar ossification located between the parapophysis of the sixth vertebra and the first or second dorsal-fin pterygiophore that is present in many loricariids, the Astroblepidae and the Scoloplacidae and occurs as an unossified tendon in callichthyids (Schaefer, 1990: 193; Armbruster, 2004: 32). In the Astroblepidae, Scoloplacidae, and many loricariids the posterior tip of the lateral bone contacts the second dorsalFig. 45. Lateral view of portion of the dorsal-fin and associated elements (left side) of Pterygoplichthys sp. (modified from of Schaefer, 1987: fig. 17c) (a), and Pterosturisoma microps (MZUSP 79909, 75.9 mm SL) (b). Arrow points to condyle (a) and chain-like structure (b). Scale bar = 1 mm. Systematics of Lamontichthys with the description of new species 556 fin pterygiophore (Bailey & Baskin, 1976; Schaefer, 1987: 26). This condition occurs in Lamontichthys, Harttia, Hypostomus, Loricaria, and Neoplecostomus among examined taxa (Fig. 46a). In Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys although present, the posterior tip of the lateral bone does not contact any pterygiophore (Fig. 46b). Farlowella lacks a connecting bone. Pectoral fin and girdle 60. Number of branched pectoral-fin rays: (0) 6; (1) 7 (CI = 100; RI = 100). The majority of the Siluriformes, including the more basal taxa, have eight or more branched rays in the pectoral-fin (de Pinna, 1996: 37). However, in the Loricariidae there is a reduction of this number to five to seven rays. Neoplecostomus, the Hypostominae, the Ancistrinae and the majority of the members of the Loricariinae and Hypoptopomatinae possess six branched rays in the pectoralfin (Schaefer, 1987, 1998). Schaefer (1998: 399) considered the presence of seven branched rays in the pectoral-fin as a derived condition within the Hypoptopomatinae. Among the Loricariinae, all species of Lamontichthys (including L. parakana), Harttia leiopleura, and Rineloricaria daraha (Rapp Py Daniel & Fichberg, 2008) possess seven branched rays, while some species of Farlowella possess only five (Boeseman, 1971). The presence of seven branched rays in the pectoral-fin was originally proposed as a diagnostic character for Lamontichthys by Isbrücker & Nijssen (1976, 1978b). 61. Length of cleithrum symphysis relative to coracoid symphysis: (0) similar to twice as short; (1) twice as long (CI = 100; RI = 100). The cleithrum and coracoid in loricariids articulate with their counterparts by means of interdigitating sutures along their symphyses, the extension of which is variable, a feature previously observed by Rapp-Py Daniel (1997: character 142). In Lamontichthys, Harttia, Farlowella, Hypostomus, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the length of the symphysis of the cleithrum is approximately equal to twice as short as the coracoid symphysis (Fig. 47). Alternatively, in Loricaria, Pseudoloricaria, and Rineloricaria, the symphysis of the cleithrum is twice as long as the coracoid symphysis. 62. Bony lamina on ventrolateral portion of coracoid: (0) absent; (1) present (CI = 50; RI = 75). The ventral surface of the pectoral girdle of loricariids possesses a fossa between the cleithrum and coracoid, termed the abductor fossa or arrector fossa that lodges the arrector ventralis profundus and arrector ventralis superficialis muscles, responsible for the movement of the pectoral fin (Schaefer, 1987: 24; 1991: 18). In Lamontichthys avacanoeiro, L. parakana (the latter species not included in the analysis), Harttia, Hypostomus, and Neoplecostomus, there is no bony lamina covering the fossa, resulting in a complete exposure of the arrector fossa (Fig. 48a). Within the Loricariinae, Lamontichthys filamentosus, L. llanero, L. maracaibero, L. stibaros, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys possess a bony lamina on the ventrolateral region of the coracoid that covers the lateral portion of the arrector fossa (Figs. 47 and 48b). This lamina connects the cleithrum anteriorly to the coracoid posteriorly and it was previously discussed by Schaefer (1987: 24). A third condition of this character was proposed by Schaefer (1987: 24; 1991: 18; 1998: 397) as synapomorphic for the Hypoptopomatinae a taxon not included in the present study. Although Lamontichthys avacanoeiro and L. parakana lack a bony lamina in the ventrolateral portion of the coracoid, Fig. 46. Dorsal view of second dorsal-fin pterygiophore, spinelet, dorsal-fin spine and lateral bone of Lamontichthys stibaros (FMNH 84111, 62.4 mm SL) (a), Rineloricaria sp. (MZUSP 23748, 91.5 mm SL) (b), and Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL) (c). Scale bar = 1 mm. A. de C. Paixão & M. Toledo-Piza 557 these two species possess a thin bony plate, covered by odontods, embedded in the skin and firmly attached to the coracoid in the same position as the osseous lamina in the other taxa. These two species were coded as “0”. each process close to each other or connected by ligaments (uninformative). In the Loricariidae each basipterygium possess a pair of anterior processes, one internal and one lateral (Schaefer, 1987: 19) or anteromesial and anterolateral processes, respectively (Armbruster, 2004: 37). Different types of contact between the anteromesial processes of the basipterygia occur among examined taxa. In members of the subfamily Loricariinae, the contralateral anteromesial processes are either not in contact, or contact each other only at their distal tips (Fig. 49a, b). The remaining loricariids possess additional regions of contact and in Neoplecostomus they are in contact along their entire medial margins (Fig. 49c). In Lamontichthys stibaros, the distal tips of the anteromesial processes are connected by ligaments. 64. Orientation of anteromesial processes of basipterygium: (0) antero-medial; (1) medial (CI = 100; RI = 100). Harttia possesses the anteromesial processes of the basipterygium medially directed, a condition previously reported by Rapp Py-Daniel (1997: character 152) for the genus. 65. Relative width of two laminar expansions of anterolateral process of basipterygium: (0) dorsal wider than ventral; (1) dorsal and ventral of similar widths; (2) dorsal narrower than ventral (CI = 100; RI = 100). In loricariids, the anterolateral process of the basipterygium possesses two laminar expansions for the attachment of the arrector dorsalis muscles (external process ridge of Shelden, 1937). One of these expansions is oriented ventral or ventrolaterally, and the other dorsal or dorsolaterally. Rapp Py-Daniel (1997: character 155) previously reported differences in the relative width of these laminar expansions in the Loricariinae. In Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys both expansions are well developed and of similar widths. In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal expansion is considerably narrower than the ventral. Hypostomus and Neoplecostomus have the dorsal expansion of the anterolateral process of the basipterygium considerably wider than the ventral. 66. Presence and relative size of lateropterygium: (0) large; (1) medium; (2) small; (3) absent (CI = 100; RI = 100). The lateropterygium is a bony structure that is connected with the lateral margin of the basipterygium dorsal to the insertion of the pelvic-fin rays, and is present in the Astroblepidae and Loricariidae (Shelden, 1937; Howes, 1983: 336). Armbruster (2004: 39) observed variation in the form of the lateropterygium among loricariids. Due to the difficulty in coding the variation observed in the format of the lateropterygium in the taxa examined in this study, such variation was coded in terms of differences in the relative size of the structure. Neoplecostomus and Hypostomus possess a relatively Fig. 47. Ventral view of the pectoral girdle of Lamontichthys filamentosus (LACM 41741-9, 119.4 mm SL). Arrow points to region of cleithrum and coracoid symphyses. Cartilages not represented. Scale bar = 3 mm. Fig. 48. Ventral view of ventrolateral portion of the pectoral girdle of Lamontichthys avacanoeiro (MZUSP 61974, 113.7 mm SL, paratype) (a), and L. filamentosus (LACM 41741-9, 119.4 mm SL) (b). Scale bar = 1 mm. Pelvic fin and girdle 63. Contact between internal anterior processes of basipterygium: (0) in contact along their entire medial margins; (1) in contact anteriorly and posteriorly at midline, with a small foramen in between; (2) not in contact, with distal tip of Systematics of Lamontichthys with the description of new species 558 large lateropterygium, its size approximately twice the length of that structure in Lamontichthys and Harttia (coded as having a medium sized lateropterygium) (Fig. 49). In the latter two genera the lateropterygium is twice the size of that structure in Farlowella, Loricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, taxa with a considerably small lateropterygium. Howes (1983: 336) proposed that the lack of a lateropterygium is derived in the subfamily Loricariinae, a condition herein observed in Pseudoloricaria. Anal-fin The anal-fin in the majority of loricariids is formed by one relatively large anterior unbranched ray, followed by four branched rays, all supported by five pterygiophores. The anal-fin pterygiophores have the proximal and medial radials fused, with only the distal radial present as a separate element (Schaefer, 1987: 18). 67. First anal-fin pterygiophore: (0) completely covered by skin; (1) with small exposed area; (2) with large exposed area (uninformative). Neoplecostomus possesses the first anal-fin pterygiophore completely covered by skin, lacking any exposed surface and Hypostomus possesses only one small exposed area. In all examined taxa of the Loricariinae the first anal-fin pterygiophore has a relatively large exposed area that supports dermal plates. 68. Centrum of articulation of first anal-fin pterygiophore: (0) centrum 15; (1) centra 12, 13 or 14 (CI = 100; RI = 100). The articulation of the first anal-fin pterygiophore with the vertebral column in all examined taxa of the Loricariinae is on centra 12, 13 or 14. In Farlowella, Loricaria, Sturisomatichthys, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma, the articulation is on centra 12 or 13 and in Lamontichthys and Harttia the articulation is slightly posterior, on centra 13 or 14. In both cases, most often, the articulation is on centrum 13. In the Astroblepidae and Callichthyidae, the articulation of the first anal-fin pterygiophore with the vertebral column is on centra 17, 18 or 19 and in the Loricariidae it varies from centra 13 to 17 (Schaefer, 1987: 25). Within loricariids, in the Hypostominae and Ancistrinae the articulation varies from centra 14 to 17, while in the Hypoptopomatinae and Loricariinae on centrum 13. This latter condition was proposed by that author as synapomorphic for the family Loricariidae. 69. Relative distance of adjacent proximal portions of first three anal-fin pterygiophores: (0) relatively distant; (1) relatively close; (2) in contact (CI = 66; RI = 80). The anal-fin pterygiophores of the majority of loricariids are expanded along the anteroposterior axis. The degree of separation among the proximal region of the first three analfin pterygiophores varies among taxa, and three distinct conditions were defined by Rapp Py-Daniel (1997: character 122). Hypostomus has the proximal tips of the first three analfin pterygiophores relatively separate from each other (Schaefer, 1987: fig. 11a). In Harttia, Loricaria, Fig. 49. Dorsal view of the pelvic girdle and lateropterygium of (a) Pterosturisoma microps (MZUSP 79909, 75.9 mm SL), (b) Lamontichthys stibaros (FMNH 84111, 62.4 mm SL), and (c) Neoplecostomus ribeirensis (MZUSP 100920, 45.3 mm SL). Scale bar = 1 mm. A. de C. Paixão & M. Toledo-Piza 559 Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the proximal regions of the first three anal-fin pterygiophores are less separate, but are not in contact, while in Lamontichthys and Farlowella the proximal tips of the first three anal-fin pterygiophores are in (or almost) in contact (Figs. 39-41). Caudal-fin 70. Number of principal caudal-fin rays: (0) 16 (i,7+7,i); (1) 14 (i,6+6,i); (2) 11-12 (i,5+5,i; i,5+4,i) (CI = 100; RI = 100). There is a trend toward a reduction in the number of principal caudal-fin rays within the Siluriformes. Diplomystidae has 18 principal rays, but most Siluriformes possess 17 or fewer principal rays in the caudal-fin (Lundberg & Baskin, 1969: 35). Members of the Loricariidae usually possess 16 principal rays in caudal-fin (Schaefer, 1991: 17). In the subfamily Loricariinae there is a reduction of this number to 11-14 principal rays (Lundberg & Baskin, 1969: 35; Schaefer, 1987: 17; 1991: 17). Lamontichthys, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess 14 principal caudal-fin rays. Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria possess 11-12 principal caudal-fin rays. 71. Relative length and shape of upper and lower lobes of hypural plate: (0) symmetric, posterior border vertically aligned; (1) asymmetric, lower lobe extending beyond posterior margin of upper lobe; (2) symmetric, posterior border “V”- shaped (uninformative). In the Loricariidae, the five hypurals and the uroneural are fused forming the “hypural plate”, the parahypural is fused to hypurals 1 and 2; the uroneural and/or the epural are fused to hypurals 3, 4 and 5. Within the Loricariidae there is variation in the shape of the posterior border of the hypural elements (Schaefer, 1987: 25). Neoplecostomus possesses a vertical posterior border with symmetric caudal lobes. In the Loricariinae the caudal fin-lobes are also symmetric, however the posterior border is “V” shaped due to the more posteriorly elongate median portion of the hypural plate. This condition was proposed by Schaefer (1987: 25) as synapomorphic for the subfamily Loricariinae. Asymmetric caudal lobes occur in most loricariids including members of the Hypostominae (Schaefer, 1987: 25), represented in this study by Hypostomus. 72. Shape of hypurapophysis: (0) short, robust, approximately triangular; (1) short, robust, approximately quadrate; (2) relatively elongate, robust, keel-shaped; (3) broad, laminar, wing-shaped (CI = 100; RI = 100). The hypurapophyses are projections on the parahypural and first and second hypurals of the caudal-fin skeleton of the Siluriformes, which serve as the insertion site for muscles involved in the movement of the caudal-fin rays (Schaefer, 1987: 17). Loricariids possess hypurapophysis type C (Lundberg & Baskin, 1969: 14), the most common among the Siluriformes in which the primary hypurapophysis is continuous with a secondary hypurapophysis on hypurals 1 and 2. In the present study, four different conditions regarding shape of the hypurapophysis are recognized. Neoplecostomus and many loricariids possess a short and robust hypurapophysis, triangular to approximately quadrateshaped. Within the Loricariinae, Harttia possesses a robust hypurapophysis, relatively wide and keel-shaped, and in Lamontichthys, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the structures are broad, laminar and wingshaped (Figs. 43 and 50). 73. Relative length of hypurapophysis: (0) short, not projecting to second preural centrum; (1) long, projecting to second preural centrum (CI = 100; RI = 100). In loricariids in general, the hypurapophysis is short and does not project anteriorly to the second preural centrum. However, in all taxa of the Loricariinae examined the hypurapophysis extends anteriorly to the second preural centrum (Figs. 43 and 50). 74. Process on ventral surface of hypurapophysis: (0) absent; (1) present (uninformative). The ventral surface of the hypurapophysis of Lamontichthys avacanoeiro possesses a narrow ossified process posteroventrally oriented, probably serving as an additional site for the attachment of the caudal-fin musculature (Fig. 50; Schaefer, 1987: 17). There are no reports of any process on the hypurapophysis of other Siluriformes. 75. Presence and relative size of epural: (0) large, length approximately equal to height of lower lobe of hypural plate; (1) small, length shorter than 1/2 of height of lower lobe of hypural plate; (2) absent as a separate element (CI = 40; RI = 25). The Siluriformes primitively possess a single epural, relatively large, separate from the dorsal hypurals (Lundberg & Baskin, 1969: 11). Among loricariids, this condition occurs in the Neoplecostominae, Hypoptopomatinae, and some Hypostominae, while in the Loricariinae and many Hypostominae there is a tendency of fusion of the epural to hypurals or reduction in epural size (Fig. 43; Schaefer, 1987: 17). Rapp Py-Daniel (1997: character 127) previously reported variation on the relative size of the epural in the Loricariinae. Lamontichthys filamentosus, L. llanero, L. stibaros, L. avacanoeiro, Harttia, Pseudoloricaria, Pterosturisoma, and Sturisoma possess a separate epural. However, it is a relatively small ossification, shorter than half the height of the lower lobe of the hypural plate (Fig. 50). The epural is lacking as a separate element in L. maracaibero, Farlowella, Loricaria, Rineloricaria, and Sturisomatichthys. 76. Notch at median posterior border of hypural plate: (0) present, elongate, extending to 1/2 of length hypural plate; (1) present, extending to approximately 1/4 length of hypural plate; (2) extremely reduced or absent (uninformative). The hypural plate of loricariids possesses a notch at its posterior median border, demarcating the separation between Systematics of Lamontichthys with the description of new species 566 reviewer. 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