A new genus of river snails, Bakyietaia (Mollusca, Viviparidae), from South China and the Indochinese Peninsula

1 European Journal of Taxonomy 1005: 1–64 https://doi.org/10.5852/ejt.2025.1005.2985 europeanjournaloftaxonomy.eu ISSN 2118-9773 2025 · Zhang L.-J. et al. This work is licensed under a Creative Commons Attribution License (CC BY 4.0) Received: 29 July 2024 • Accepted: 7 April 2025 • Published: 31 July 2025 Topic editor: Magalie Castelin • Section editor: Thierry Backeljau • Desk editor: Pepe Fernández Monograph urn:lsid:zoobank.org:pub:BAD3B10F-13AB-43E3-8B52-0B613A992602 A new genus of river snails, Bakyietaia (Mollusca, Viviparidae), from South China and the Indochinese Peninsula Le-Jia ZHANG 1+ , Yu-Hsiu YEN 2,*+ , Zhe-Yu CHEN 3 , Li-Na DU 4 , Ting Hui NG 5  & Thomas von RINTELEN 6,* 1 Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650023, China. 1 Museum für Naturkunde, Leibniz Institut für Evolutions und Biodiversitätsforschung, Berlin 10115, Germany. 1 Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin, Nay Pyi Taw, 05282, Myanmar. 2 Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 80424, Taiwan. 3 Parasitology Research Group, Department of Veterinary Biosciences, Faculty of Science, The University of Melbourne, Parkville VIC 3010, Australia. 3 Department of Life Sciences, Natural History Museum, London SW7 5BD, UK. 4 Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Normal University, Ministry of Education, Guilin, Guangxi 541004, China. 5 Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota, Malaysia. 5 Lee Kong Chian Natural History Museum, National University of Singapore, 2 Conservatory Drive, Singapore 117377, Republic of Singapore. 6 Museum für Naturkunde, Leibniz Institut für Evolutionsund Biodiversitätsforschung, Berlin 10115, Germany. * Corresponding authors: [email protected] – [email protected] 1 Email: [email protected] 3 Email: [email protected] 4 Email: [email protected] 5 Email: [email protected] + These two authors contributed equally to the manuscript Abstract. A new genus of the river snail family Viviparidae, Bakyietaia Zhang, Yen & von Rintelen gen. nov., is described based on a comprehensive study of its morphology, anatomy, mtDNA (COI), ecology and distribution. This genus is widely distributed in South China and the Indochinese Peninsula. It can be distinguished from all other viviparid genera, especially Angulyagra, Sinotaia and Anulotaia, by characters of the columellar lip of the shell, the operculum and the marginal teeth of radula. Based on an integrative taxonomic approach, 17 species are assigned to this new genus and described here, including 7 new combinations and 10 new species: Bakyietaia subcostata gen. et comb. nov., B. polyzonata gen. et European Journal of Taxonomy 1005: 1–64 (2025) 2 comb. nov., B. boettgeri gen. et comb. nov., B. duchieri gen. et comb. nov., B. guangdungensis gen. et comb. nov., B. mutica gen. et comb. nov., B. wilhelmi gen. et comb. nov., B. chenghuang Zhang, Yen & von Rintelen gen. et sp. nov., B. jingweiae Yen, Zhang & von Rintelen gen. et sp. nov., B. liusanjieae Zhang, Yen & von Rintelen gen. et sp. nov., B. avisvenatoris Yen, Zhang & von Rintelen gen. et sp. nov., B. liangzhuorum Yen, Zhang & von Rintelen gen. et sp. nov., B. luikongi Yen, Zhang & von Rintelen gen. et sp. nov., B. fontinalis Zhang, Yen & von Rintelen gen. et sp. nov., B. naiadica Zhang, Yen & von Rintelen gen. et sp. nov., B. luuemxlong Zhang, Yen & von Rintelen gen. et sp. nov. and B. indrapura Zhang, Yen & von Rintelen gen. et sp. nov. The monophyly of all morphospecies is supported by the COI phylogeny. Radular characters, especially the number of cusps of the outer marginal teeth, are considered valuableintheclassificationofspeciesofBakyietaia with similar shells. Keywords. Angulyagra, biogeography, gastropod, systematics, taxonomy. Zhang L.-J., Yen Y.-H., Chen Z.-Y., Du L.-N., Ng T.H. & von Rintelen T. 2025. A new genus of river snails, Bakyietaia (Mollusca, Viviparidae), from South China and the Indochinese Peninsula. European Journal of Taxonomy 1005: 1–64. https://doi.org/10.5852/ejt.2025.1005.2985 Introduction Viviparidae J.E. Gray, 1847 (river snails) is a family of freshwater snails comprising 125 to 150 valid described extant species with a worldwide native distribution except for South America and Antarctica (Strong et al. 2008). The Viviparidae have a rich fossil record (Prashad 1928), and many extinct species are found outside the current geographic range of this family, such as in the Middle East (Sivan et al. 2006) and South America (Ghilardi et al. 2011). The oldest fossils can be traced back to the Early to Middle Jurassic: Viviparus sangongheensis Zhu, 1994 from Xinjiang, China (Early Jurassic; Zhu 1994) and Bathonella scotica (Tate, 1873) from England, UK (Middle Jurassic; Tracey et al. 1993). The early origin, abundant fossil record and (almost) worldwide distribution of the Viviparidae has drawn many researchers’ attention to the systematics, evolutionary history and biogeography of this family (Sengupta et al. 2009; Schultheiß et al. 2014; Zhang et al. 2015; Hirano et al. 2019a, 3019b, 2023; Stelbrink et al. 2020; Ye et al. 2020). South China and Southeast Asia harbour the highest biodiversity of Viviparidae (Strong et al. 2008; Zhang et al. 2015; Stelbrink et al. 2020). Yunnan Province in Southwestern China harbours ten genera, including four endemic ones (Anularya Zhang & Chen, 2015; Dalipaludina Zhang, 2023; Margarya Nevill, 1877; Tchangmargarya He, 2013) and at least 15 endemic species (Zhang et al. 2023). Southeast Asia harbours 12 genera, including four endemic to the Indochinese Peninsula (Anulotaia Brandt, 1968; Eyriesia Fischer, 1885; Taia Annandale, 1918; Trochotaia Brandt, 1974) and two endemic to insular Southeast Asia (Celetaia Clench, 1966; Torotaia F. Haas, 1939) (Molluscabase 2023). However, Viviparidae from this region are understudied, with only a few recent studies focussing on this hotspot of viviparid diversity (Zhang et al. 2015; Stelbrink et al. 2019, 2020; Zhang et al. 2023). Rao (1925) established a new genus in the Viviparidae, Dactylochlamys, for a single species with many smooth, strong keels on the shell, endemic to the Manipur Valley of India, Paludina oxytropis Benson, 1836.However,Rao(1931)lateridentified Dactylochlamys Rao, 1925 as a junior homonym of the ciliate Dactylochlamys Lauterborn, 1901; therefore, Angulyagra Rao, 1931 was established as a replacement name for this genus. Angulyagra soon became a ‘wastebasket taxon’ for species from Asia possessing a shell with many smooth, strong keels (Prashad 1928; Yen 1939, 1943; Starobogatov 1970; Liu et al. 1995). However, most of these species are distinct from the type species of Angulyagra based on characters of the shell, radula, operculum, and anatomy. Therefore, a systematic revision of Angulyagra is needed. Here, we revise the species of Angulyagra from South China and the Indochinese Peninsula based on their morphology (shell, operculum, radula), ecology, distribution and variation in the mitochondrial ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 3 COI gene. Our integrative study has revealed that there are at least 17 species within this group, and all of these species of Angulyagra should actually be assigned to a new genus described here: Bakyietaia Zhang, Yen & von Rintelen gen. nov. Material and methods Material Typespecimensoftenviviparidspeciesfromfiveinstitutions(NaturalHistoryMuseum,London (NHMUK); Gymnasium der Franziskaner, Bozen (GFBI); Naturhistorisches Museum, Vienna (NHMW); Naturmuseum Senckenberg, Frankfurt (SMF); Muséum national d’Histoire naturelle, Paris (MNHN)) have been examined. The type specimens of nine new species described here have been deposited in the Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming (KIZ) and the Museum für Naturkunde, Berlin (ZMB), non-types are also in the collections of Le-Jia Zhang (ZLJ) and Yu-Hsiu Yen (YHY). In addition, comparative non-type material held in ZMB, KIZ and and the BORNEENSIS Collection, Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah (BOR) have also been examined. The specimens used for the morphological and molecular analysis were collected during 2006–2022. A two-month expedition for collecting species of Viviparidae from rivers, springs, lakes and wetlands of Southern China was conducted in early 2022. Altogether 73 sites were sampled and are illustrated in the map (Fig. 1). Fig. 1. Map of the main river basins in South China and the Indochinese Peninsula with the collecting sites of species of Bakyietaia Zhang, Yen & von Rintelen gen. nov. Sites with more than one species are indicated by an arrow and multiple species symbols on a grey background. The symbol “?” indicates sites with species of Bakyietaia onlyidentifiedtogenuslevel. European Journal of Taxonomy 1005: 1–64 (2025) 4 Examination of morphology The height (H) and width (W) of shells of mature and complete specimens were measured with an electronic calliper to a precision of 0.1 mm. The mass (M) of several selected shell specimens was measured by an electronic scale to a precision of 0.01 g. Selected shells comprised nine specimens of Angulyagra oxytropis (Benson, 1836) and 44 specimens of species of Bakyietaia gen. nov. The shells were completely dry and the mass was constant. All specimens were photographed in a consistent orientation using a Sony alpha 7R 4 camera. Radulae were extracted by dissection, cleaned by boiling in 1% NaOH solution for half an hour and rinsed with distilled water. Radulae were coated with gold and imaged with a Zeiss EVO LS10 scanning electron microscope. Terms used for describing the operculum follow Zhang & von Rintelen (2021). Abbreviations for features of the radula: ct = central teeth imt = inner marginal teeth lt = lateral teeth omt = outer marginal teeth. Molecular methods DNAwasextractedfrom10–20mgfoottissuefromeachsnail,usingamollusc-specificCTAB/ chloroform extraction protocol (Winnepenninckx et al.1993). A fragment (570 bp) of the mitochondrial cytochromecoxidasesubunitI(COI)genewasamplifiedthroughpolymerasechainreaction(PCR)with thefollowingprimerpair:LCO1490,5′-GGTCAACAAATCATAAAGATATTGG-3′andCOX-B7R, 5′-ACCACCAGCTGGATCAAAAA-3′.(Schultheißet al.2011)PCRamplificationswereconducted in25μlvolumesunderthefollowingcyclingconditions:initialdenaturingstepat94°Cfor10min, followedby30cyclesof94°Cfor1min,50°Cfor1min,and72°Cfor1min,withafinalextensionstep of10minat72°C.ThepurificationandsequencingwereconductedbyMacrogenEurope,Amsterdam, Netherlands. Sequence and phylogenetic analyses 140 new COI sequences of species of Viviparidae and 16 sequences of 13 genera of the subfamily Bellamyinae Rohrbach, 1937, mostly from Stelbrink et al. (2020), were included in the present study (Supp.file1). Viviparus contectus (Millet, 1813) of the subfamily Viviparinae J.E. Gray, 1847 was selected as outgroup based on Stelbrink et al. (2020). Sequences were aligned using MUSCLE as implemented in Geneious Prime 2020 (https://www.geneious.com). Genetic distances were calculated using MEGA X (Kumar et al. 2018). TN93+G+Iwassuggestedasthebest-fitmodelofsequenceevolutionforourdatasetbymeansofthe Akaike and Bayesian information criteria in MEGA X. A Bayesian inference (BI) analysis was performed with MrBayes ver. 3.2.6 (Ronquist et al. 2012) as implemented in Geneious Prime 2020 with four independentchainsfor5000000generations,samplefreq=1000,burnin=25%,andweconfirmed that convergence was reached based on the trace plots generated in Geneious Prime 2020. A maximum likelihood (ML) analysis was conducted with RAxML as implemented in Geneious Prime 2020, with nodal support estimated by 1000 bootstrap replicates (Kozlov et al. 2019). Species delimitation Assemble Species by Automatic Partitioning (ASAP) (Puillandre et al. 2020) was performed on the ASAP web platform (https://bioinfo.mnhn.fr/abi/public/asap/) using the Jukes Cantor (JC69) model and simplegeneticdistancecalculatedwithdefaultsettings:probability.01,seedvalue−1,geneticdistances between 0.005 and 0.05. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 5 Fig. 2. Bayesian inference phylogram of the species of Bakyietaia Zhang, Yen & von Rintelen gen. nov. and some related viviparid genera based on cytochrome c oxidase subunit I (COI) with operational taxonomic unit (OTU) assignments. Numbers at nodes indicate Bayesian posterior probabilities (left) and maximum likelihood bootstrap support values (right). Supporting values lower than 0.5/50 are not presented and are shown as ‘-’. Background in colours indicate new combinations (blue) and new species (orange). ASAP: Assemble Species by Automatic Partitioning. Scale bar = 0.04 substitutions per site. European Journal of Taxonomy 1005: 1–64 (2025) 6 Table 1. Shell measurements of species of Angulyagra Rao, 1931 and Bakyietaia Zhang, Yen & von Rintelen gen. nov. Abbreviations: H = height; M = mass; N = measured specimens; n = measured completely dry shells; W = width. Species N n H (mm) W (mm) W/H M (g) Angulyagra oxytropis 9 9 34.60 ± 3.77 27.15 ± 3.79 0.78 ± 0.03 1.01 ± 0.28 Bakyietaia polyzonata 326.60 ± 1.91 19.19 ± 1.30 0.72 ± 0.01 – Bakyietaia subcostata 10 27.17 ± 3.64 20.25 ± 1.75 0.75 ± 0.05 2.52 ± 0.36 Bakyietaia boettgeri 9 7 26.76 ± 6.67 18.87 ± 5.12 0.70 ± 0.04 2.16 ± 2.78 Bakyietaia duchieri 232.88 ± 1.00 24.46 ± 1.77 0.74 ± 0.03 – Bakyietaia guangdungensis 7 3 20.87 ± 0.93 14.57 ± 0.61 0.70 ± 0.03 0.78 ± 0.18 Bakyietaia mutica 11 222.14 ± 1.74 15.49 ± 1.06 0.70 ± 0.04 0.84 ± 0.16 Bakyietaia wilhelmi 10 10 25.53 ± 3.72 17.28 ± 2.11 0.68 ± 0.04 1.63 ± 0.97 Bakyietaia chenghuang 3 2 23.70 ± 5.37 17.67 ± 3.42 0.74 ± 0.03 1.19 ± 0.02 Bakyietaia jingweiae 9 9 26.79 ± 5.37 17.67 ± 3.42 0.66 ± 0.04 1.94 ± 1.90 Bakyietaia liusanjieae 12 1 25.69 ± 3.35 18.98 ± 2.31 0.74 ± 0.04 3.00 Bakyietaia avisvenatoris 619.78 ± 1.67 14.50 ± 1.48 0.73 ± 0.03 – Bakyietaia liangzhuorum 8 4 25.25 ± 3.07 18.13 ± 2.33 0.72 ± 0.04 0.77 ± 0.22 Bakyietaia luikongi 320.66 ± 0.70 15.44 ± 0.62 0.75 ± 0.02 – Bakyietaia fontinalis 8 1 24.25 ± 2.59 17.44 ± 1.84 0.72 ± 0.03 0.40 Bakyietaia naiadica 325.73 ± 0.62 18.02 ± 0.31 0.70 ± 0.01 – Bakyietaia luuemxlong 423.56 ± 2.58 16.49 ± 1.29 0.70 ± 0.02 – Bakyietaia indrapura 3 3 26.92 ± 2.45 17.67 ± 1.40 0.66 ± 0.01 1.07 ± 0.41 Fig. 3. Comparison of Bakyietaia Zhang, Yen & von Rintelen gen. nov. and Angulyagra Rao, 1931 with respect to parameters H and W/H (A), and with respect to parameters H and log (10M) (B). ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 7 Results Genetic differentiation, phylogeny and species delimitation The COI p-distances within species of Bakyietaia gen. nov. are 0–1.42% and between species of Bakyietaia are 1.68%–7.53%; the COI p-distances between Bakyietaia and other genera of Viviparidae are 8.45%–15.65%. The phylogenetic trees reconstructed by BI and ML based on COI are congruent, but the ML tree (Supp.file2) contains several substaintial polytomies and, therefore, only the BI tree is displayed (Fig. 2). The new genus Bakyietaia gen. nov. is monophyletic with high and low support in the BI and ML trees, respectively, and it is distinct from all other genera of Viviparidae included in the analysis. The type species of Angulyagra (Angulyagra oxytropis) is not included in the current tree. Angulyagra costata (Quoy & Gaimard, 1834) clusters with Torotaia cf. mainitensis (Bartsch, 1907) with a high degree of support and is not closely related to any species of Bakyietaia. Filopaludina Habe, 1964 (including type species F. bengalensis (Lamarck, 1822), F. doliaris (A. Gould, 1844), F. javanica (von dem Busch, 1844), F. decipiens (Tapparone Canefri, 1883)) is monophyletic with moderate to high support and in the BI analysis, and is recovered as the tentative sister clade of Bakyietaia with low support. The 17 morphologicallyidentifiedspeciesofBakyietaia are each recovered as monophyletic, mostly with high support values, although the support for some species such as B. liangzhuorum gen. et sp. nov. and B. wilhelmi is weak to moderate. The 17 groups/operational taxonomic units (OTUs) given by the ASAP analysis were the best partition from the lowest ASAP-score under all default settings. The two ASAP results are consistent with the phylogenyandmorphologicalidentifications. Statistics of shell characters The shell measurements reveal that Angulyagra oxytropis has a larger, more compact but lighter shell compared to species of Bakyietaia gen. nov. The shell height of Angulyagra oxytropis is larger than that of any species of Bakyietaia, and the larger W/H of Angulyagra oxytropis shows that it has a relatively more compact shell regardless of size (Table 1, Fig. 3A). Angulyagra oxytropis always has a larger shell than species of Bakyietaia when the mass of both is the same; correspondingly, Angulyagra oxytropis always has a much lighter shell than species of Bakyietaia when the height of both is the same (Fig. 3B). Values are arithmetic means and standard deviations of height (H) and width (W) of N measured specimens and mass (M) of n measured completely dry shells. Systematics Class Gastropoda Cuvier, 1795 Order Architaenioglossa Haller, 1892 Family Viviparidae J.E. Gray, 1847 Subfamily Bellamyinae Rohrbach, 1937 Genus Angulyagra Rao, 1931 Dactylochlamys Rao, 1925: 132 [non Dactylochlamys Lauterborn, 1901 (Ciliophora), junior homonym]. Angulyagra Rao, 1931: 301. Type species Paludina oxytropis Benson, 1836, by original designation. European Journal of Taxonomy 1005: 1–64 (2025) 8 Diagnosis “The shell is of large size, conical, thin but ornamented with prominent smooth spiral ridges which are concaveontheinternalsurface.Thebaseissomewhatflattened.Theumbilicusisbroadlyrimatewitha broadchanneldescendingdownwardsfromit.Themantlehasenlargedandhighlyvascularfinger-shaped processes on the margin” (Rao 1925). Remarks The shell of Angulyagra is most similar to that of Torotaia or Dalipaludina, all of them possessing a large thin shell with strong keels, acute apex, and simple columellar lip. It can be distinguished from the latter two genera based on the following combination of characters: teleoconch whorls with strong keels obviously darker than the rest of the shell surface in colour, open umbilicus bordered by a strong keel; operculum with growth lamellae on exterior surface and radial striae on interior surface; radula with narrow marginal teeth, the width of both inner and outer marginal teeth is only half that of the lateral teeth,andoutermarginalteethwith15tinycusps;highlyvascularfinger-shapedprocessesonthemantle margin. Angulyagra oxytropis (Benson, 1836) Fig. 4 Paludina oxytropis Benson, 1836: 745 (type locality not stated in the original description). Paludina pyramidata von dem Busch, 1844 in Philippi 1842–1850:113,pl.1figs3–4. Vivipara oxytropis – Preston 1915: 84. — Annandale & Seymour Sewell 1920: 113. — Annandale 1921: 544–552,figs2–5. Dactylochlamys oxytropis – Rao 1925: 132. Angulyagra oxytropis –Rao1931:301.—SubbaRao1989:51,fig.70.—Preeceet al. 2022: 94, fig.38a. Diagnosis Shell large, fragile and lightweight. Each teleoconch whorl with three strong keels, open umbilicus bordered by one strong keel. Operculum with growth lamellae on exterior surface and radial striae on interior surface. Inner and outer marginal teeth of radula both nearly half of lateral tooth in width. Mantle edgewithanumberoffinger-shapedprocesses. Material examined Holotype BENGAL•drypreservedspecimen;NHMUK.1879.12.26.120. Other material INDIA • 8 specs (preserved dry, 6 adults and 2 juveniles); Manipur, Loktak “Logtak Lake”; NHMUK.1974.03.7.1toNHMUK.1974.03.8•2 specs (preserved dry); Assam, Manipur, Loktak Lake; NHMUK.2019.04.31. Description Shell (Fig. 4A–F) large, broadly conical, thin, lightweight, fragile, olive to greenish brown; up to six whorls at adulthood, including one relatively smooth protoconch whorl, apex acute; each teleoconch whorl with three strong primary keels of darker colour, the strongest keel above suture, one to two weaker smooth secondary keels located between primary keels; base of shell with three to four spiral keels of darker colour, one to two weaker secondary keel located between strong primary keels; aperture ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 9 ovate, inner shell surface bluish white, with obvious grooves corresponding to the position of the three strong keels, outer lip thin, three strong keels extending to margin of outer lip, columellar lip thin and simple; umbilicus broadly open, bordered by a strong keel. Operculum (Fig. 4G–H) corneous, transparent pale brown, rather thin; nucleus sub-central, close to inner margin; exterior surface with regularly distributed growth lamellae; interior surface with large inner opercular region and radial striae starting from nucleus; nuclear region relatively large, smooth and glossy, with veins at margin. Radularcentraltoothwithonebroadcentraldenticleandfivesmallsharpcuspsoneitherside;lateral tooth with one broad central denticle, three small sharp cusps on inner side and six small sharp cusps on outer side; inner and outer marginal teeth narrow, both nearly half of lateral tooth in width; inner marginal tooth with one broad central denticle and three small sharp cusps on either side; outer marginal toothwith15tinysharpcusps(summarizedbasedonthefigureanddescriptionfromAnnandale1921). Mantleedgewithanumberoffinger-shapedprocesses,threeoftheseprocesseslarger,eachlargeprocess correspondingtoagrooveoftheinnershellsurface;gilllamellawithabroadbaseandalongfingershaped part; about ten embryos and ten eggs in the uterus of a pregnant female (summarized based on thefigureanddescriptionfromRao(1925)andAnnandale(1921)). Remarks This species can be easily distinguished from the other viviparid species according to the remarks for the genus. As the type species of Angulyagra, A. oxytropis shows large morphological and anatomical Fig. 4. Shells and operculum of Angulyagra oxytropis (Benson, 1836). A–D. NHMUK.2019.04.31.1, Loktak Lake, India. E–F. NHMUK.2019.04.31.2, Loktak Lake, India. G–H. Operculum of NHMUK.2019.04.31.1. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum G–H. European Journal of Taxonomy 1005: 1–64 (2025) 16 Material examined Lectotype CHINA?•drypreservedspecimen;designatedbyYen(1939);NHMW68037. Paralectotype CHINA?•1spec.(preserveddry);NHMW68038. Other material CHINA•3specs(preservedinethanol);Guangxi,ChongzuoCity,LongzhouCounty,ShuikouTown, Poliu Village, outlet of an underground river in a cave; 4 Mar. 2023; KIZ.240051 to KIZ.240053. VIETNAM•11specs(preservedinethanol);NinhBinh,ReservoirnearDang,CucPhuongN.P.; ZMB.114132•1spec.(preservedinethanol);HoaBinh,TanLacdistrict,NgocLy;ZMB.114150• 3 specs (preserved in ethanol); Bac Kan, Phu Luong, Yen Ninh, Dong Dang; ZMB.114171. Description Adult shell (Fig. 7A–J) medium in size (26.60 ± 1.91 mm), thin but sturdy, conical, olive to greenish brown,withfivetosixwhorls,apexacute;teleoconchwhorlsslightlyinflatedespeciallyonbodywhorl. Shoulder angular, with three smooth primary keels and one to two weaker smooth secondary keels betweensutureandfirstkeel.Sometimes,oneadditionalweakkeellocatedbetweenfirstandsecond/ secondandthirdkeels.Shellbasewiththreetofiveweakkeels,andusuallydarkerthanotherpartsof shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, smooth and rounded. Inner layers of adult columellar lip thickened, white or orange, recurved columellar lip partially or wholly covering umbilicus, sometimes forming a callus. Operculum (Fig. 7J–K) corneous, ovate, thin, yellow to orange; exterior surface smooth; interior surface with smal nuclear region (around 1/4 of inner opercular region), with shiny grains or veins. Radular(Fig.8)(n=4)centraltoothwithonebroadcentraldenticleandfivesmallsharpcuspsoneither side;lateraltoothwithonebroadcentraldenticleandfivesmallsharpcuspsoneitherside;innermarginal toothnarrow,abouthalfoflateraltoothinwidth,withonebroadcentraldenticleandfivetosixsmall sharp cusps on either side; outer marginal tooth wide, almost same as lateral tooth in width, with 21 to 26 small sharp cusps. Fig. 8. SEM photo of the radula of Bakyietaia polyzonata (Frauenfeld, 1862) gen. et comb. nov., ZMB.114171. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 17 Remarks The newly collected specimens from Longzhou, China have a shell that is very similar to that of the lectotype. The type locality of this species was not clear from the original description, and it was considered simply as China (Yen 1939). Bakyietaia polyzonata can be distinguished from most congeners, especially Bakyietaia indrapura gen. et sp. nov., by its medium-sized, thin conical shell withinflatedwhorls,moreroundedouterlipanddistribution.TherecommendedChinesenameis 多棱越田螺. Habitat and distribution Rivers and lakes of Western Guangxi of China and Northern Vietnam. Bakyietaia subcostata (Gray, 1833) gen. et comb. nov. Figs 7–8 Paludina subcostataGray,1833inGriffith&Pidgeon1833–1834:599,pl.36fig.3(“China”). Paludomus futaii Gredler, 1889: 159 (“Peho, Kuang-tung”, refers to Bei River, Guangdong Province, China). Syn. nov. Sinotaia? futaii –Zilch1974:64,pl.7fig.9. Angulyagra subcostata – Liu et al. 1995: 14. Diagnosis Adult shell medium to large (27.17 ± 3.64 mm), rounded and thin, primary keels weak, teleoconch with weak primary keels; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 29 to 43 small sharp cusps. Material examined Holotype of Paludina subcostata CHINA•drypreservedspecimen;NHMUK.2007.01.7.1. Holotype of Paludomus futaii CHINA•drypreservedspecimen;GuangdongProvince,BeiRiver;GFBI.22. Other material CHINA – Guangdong Province•4specs(preservedinethanol);GuangzhouCity,ZhengguoTown, ZengRiver,0.7mdeepunderrock;25Sep.2019;Da-MingShileg.;ZMB.122694•3specs(preserved dry); Guangzhou City, Zhengguo Town, Zeng River, 0.7 m deep under rock; 25 Sep. 2019; Da-Ming Shileg.;YHY-BAKSUB-ZG-1,YHY-BAKSUB-ZG-18,YHY-BAKSUB-ZG-28•3specs(preserved dry); Zhaoqing City, Xiaoxiang Town, Xi River, under rock; Aug. 2021; Ji-Lin Jiang leg.; KIZ.240084 •2specs(preservedinethanol);QingyuanCity,ShitanTown,BinRiver,0.6mdeeponrock;24Sep. 2022;MrChenleg.;ZMB.122767•2specs(preserveddry);QingyuanCity,ShitanTown,BinRiver, 0.6mdeeponrock;24Sep.2022;MrChenleg.;YHY-BAKSUB-ST-1,YHY-BAKSUB-ST-4•2specs (preservedinethanol);ZhaoqingCity,HuaijiCounty,SuiRiver;15Sep.2022;ZMB.122766•1spec. (preservedinethanol);QingyuanCity,JintanTown,BinRiver;10Oct.2022;KIZ.240085•4specs (preserved in ethanol); Zhaoqing City, Fengkai County, Xi River; 19 Jan. 2024; Lejia Zhang leg.; KIZ.240086. European Journal of Taxonomy 1005: 1–64 (2025) 18 Description Adult shell (Fig. 9A–Q) medium to large (27.17 ± 3.64 mm), thin but sturdy, rounded, olive to dark brown;withfivetosixwhorls,apexacute;teleoconchwhorlsinflated,sometimesformingshoulder, with three smooth weak primary keels, with one to two weaker smooth secondary keels located between Fig. 9. Shells and operculum of Bakyietaia subcostata (Gray, 1833) gen. et comb. nov. A–D. Holotype, NHMUK.2007.01.7.1, China, photo by Jonathan Ablett. E–H. KIZ.240084, Xiaoxiang Town, Guangdong, China. I–J. ZMB.122766, Huaiji County, Guangdong, China. K. KIZ.240085, Jintan Town, Guangdong, China. L. Holotype of Paludomus futaii, GFBI.22, Bei River, Guangdong, China. M–O. YHY-BAKSUB-ZG-18 (M), YHY-BAKSUB-ZG-28 (N), ZMB.122694 (O), Zhengguo, Guangdong, China. P–Q. ZMB.122767, Shitan Town, Guangdong, China. R–S. Operculum of KIZ.240086; scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum R–S. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 19 sutureandfirstkeel,sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/secondand thirdkeels,baseofshellwiththreetofiveweakkeels;apertureovate,large,aroundhalfofshellinheight, inner shell surface bluish white to purple, outer lip thin, always with a relatively rounded periphery, columellar lip covered with thick inner shell layers, always whitish orange or pink, adult columellar lip recurved, forming a very narrow crescent-shaped callus or without this structure, columellar lip or this structure completely covering umbilicus. Operculum (Fig. 9R–S) corneous, ovate, thin, yellow; exterior surface smooth; interior surface with nuclear region small, around 1/5 of inner opercular region, with shiny grains or veins. Radular(Fig.10)(n=4)centraltoothwithonebroadcentraldenticleandfivetosixsmallsharpcusps oneitherside;lateraltoothwithonebroadcentraldenticleandfivesmallsharpcuspsoneitherside; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and four small sharp cusps on either side; outer marginal tooth wide, almost same as lateral tooth in width, with 29 to 43 small sharp cusps. Remarks Bakyietaia subcostata can be easily distinguished from most congeners based on the rounded thin shell with weak primary keels. It can be differentiated from the morphologically similar species Bakyietaia chenghuang gen. et sp. nov. based on the larger number of small cusps on the outer marginal teeth of the radula (29–43 vs 15–16). Paludomus futaii was described based on a juvenile shell of this species, and it is here placed in synonymy of B. subcostata. The recommended Chinese name is 次肋越田螺. Habitat and distribution Rock substrate in the shallow water of rivers of Guangdong Province, China. Bakyietaia boettgeri (Möllendorff, 1890) gen. et comb. nov. Figs 11–12 Paludina boettgeriMöllendorff,1890inHeude1882–1890:177,pl.10fig.6(“Hai-nan”,Hainan Province, China). Viviparus (Taia) boettgeri – Zilch 1938: 131. Angulyagra boettgeri –Yen1939:38,pl.3fig.17.—Liuet al. 1995: 14. Fig. 10. SEM photo of the radula of Bakyietaia subcostata (Gray, 1833) gen. et comb. nov., ZMB.122766. European Journal of Taxonomy 1005: 1–64 (2025) 20 Diagnosis Adultshellmediumtolarge(26.76±6.67mm),sturdy,conical,whorlsnotinflated,prominentkeel above suture; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 23 to 24 small sharp cusps. Material examined Paratypes CHINA•5specs(preserveddry);HainanIsland; O.Böttgerleg.;SMF.7651•2specs(preserveddry); Hainan Island; O.v. Möllendorff leg.; SMF.7653. Other material CHINA – Guangxi•1spec.(preservedinethanol);NanningCity,DawangtanReservoir;Aug.2019; KIZ.240087•5specs(preservedinethanol);BaiseCity,YoujiangDistrict,WulaVillage,Sanglu,0.5m deeponrocksofcreeks;17Oct.2019;Jian-ZhuoLileg.;ZMB.122687•3specs(preserveddry);same dataasforpreceding;YHY-BAKBOE-SL-1,YHY-BAKBOE-SL-2,YHY-BAKBOE-SL-18•5specs (preserved in ethanol); Guigang City, Gangnan District, Batang Village, a pond near Yapengling, 0.7 m deeponrocks;31Oct.2020;Xia-MingLileg.,ZMB.122759•1spec.(preserveddry);samedataasfor preceding;YHY-BAKBOE-BT-1•1spec.(preserveddry);ChongzuoCity,DaxinCounty,LeipingTown, HeishuiRiver,1mdeeponrocks;27Mar.2021;Yi-WenLiangleg.;ZMB.122690•4specs(preserved dry); same data as for preceding; YHY-BAKBOE-HSH-21, YHY-BAKBOE-HSH-15, YHY-BAKBOEHSH-9,YHY-BAKBOE-HSH-3•4specs(preservedinethanol);ChongzuoCity,JiangzhouDistrict, Tuozao Village, Zuo River, 0.5 to 1.5 m deep on rocks; 27 Mar. 2021; Yi-Wen Liang leg.; ZMB.122758 •3specs(preserveddry);samedataasforpreceding;YHY-BAKBOE-JZ-15,YHY-BAKBOE-JZ-14, YHY-BAKBOE-JZ-1•2specs(preservedinethanol);NanningCity,MashanCounty,ShitangVillage, 0.3mdeeponsand/mudsubstrateinthewetland;19Mar.2022;Le-JiaZhangleg.;ZMB.122734• 3 specs (preserved in ethanol); Pingguo City, Yihao Village, Bujian River, 0.5 to 1 m deep on mud substrate; 19 Mar. 2022; Le-Jia Zhang leg.; ZMB.122720. – Hainan Province •2specs(preserved dry);HainanIsland,Jetschinleg.;SMF.88400•5specs(preservedinethanol);Haikou,wetlandsnear Yangshan Reservoir; 20 Oct. 2019; bought by Sheng-Zhuo Huang on local market; ZMB.122710. Description Adult shell (Fig. 11A–R) medium to large (26.76 ± 6.67 mm), thin to thick, sturdy, conical, olive brown todarkbrown,withfivetosixwhorls,apexacute;teleoconchwhorlsnotinflated,withthreesmooth primarykeels,withonetotwoweakersmoothsecondarykeelslocatedbetweensutureandfirstkeel, sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels,baseof shellwithonetofiveweakkeels,allkeelsusuallydarkerthanrestofshellsurface,prominentkeelabove suture; aperture ovate, less than half of shell in height, inner shell surface bluish white, orange-red or dark purple, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white or orange-red, adult columellar lip recurved, forming a relatively wide crescentshaped callus, completely covering umbilicus. Operculum (Fig. 11S–T) corneous, ovate, relatively thick, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular(Fig.12)(n=3)centraltoothwithonebroadcentraldenticleandfivetosixsmallsharpcusps oneitherside;lateraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcuspsoneither side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 21 Fig. 11. Shells and operculum of Bakyietaia boettgeri (Möllendorff, 1890) gen. et comb. nov. A–C. Paratype, SMF.7651, Hainan, China. D. Paratype, SMF7653, Hainan, China. E. SMF.88400, Hainan, China. F–I. ZMB.122710, Haikou, Hainan, China. J. KIZ.240087, Nanning, Guangxi, China. K. ZMB.122687, Sanglu, Guangxi, China. L. YHY-BAKBOE-JZ-1, Jiangzhou, Guangxi, China. M. ZMB.122720, Pingguo, Guangxi, China. N. ZMB.122758, Jiangzhou, Guangxi, China. O–Q. ZMB.122690 (O), YHY-BAKBOE-HSH-9 (P–Q), Leiping, Guangxi, China. R. ZMB.122734, Mashan County, Guangxi, China. S–T. Operculum of KIZ.240087. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum K–L. European Journal of Taxonomy 1005: 1–64 (2025) 22 four small sharp cusps on either side; outer marginal tooth wide, almost same as lateral tooth in width, with 23 to 24 small sharp cusps. Remarks The newly collected specimens from Haikou City of Hainan have a shell that is very similar to that of the type specimens. Bakyietaia boettgeri can be distinguished from most congeners based on its mediumsizedtolargeconicalshellwithnon-inflatedwhorls,andstronglykeeledsuture.Somesmallindividuals of this species may be confused with Bakyietaia jingweiae Yen, Zhang & von Rintelen gen. et sp. nov. based on shell morphology, but differ by possessing fewer cusps on the outer marginal tooth (23–24 vs 26–28). The COI tree supports B. boettgeri and B. jingweiae as distinct species, and the two species are allopatric (Fig. 1). The recommended Chinese name is 伯氏越田螺. Habitat and distribution Mud, sand and rock substrate in the shallow water of rivers, lakes and wetlands of northern Hainan and southern Guangxi, China. Bakyietaia duchieri (Fischer, 1898) gen. et comb. nov. Fig. 13 Paludina duchieriFischer,1898:330–331,pl.18figs48–49(“Riv.Song-KI-Kong,àDéo-Cat”,KỳCùng River,atĐèoKhách,LạngSơn,Vietnam). Angulyagra duchieri – Starobogatov 1970: 202. — Thanh et al.2004:3–4,fig.5. Angulyagra boettgeri –Madsen&Hung2014:109,figs2(10left),(10middle)[nonPaludina duchieri Fischer, 1898]. Diagnosis Shelllarge(32.88±1.00mm),thickandsturdy,whorlsinflated,withnarrowangularshoulder; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins. Fig. 12. SEM photo of the radula of Bakyietaia boettgeri (Möllendorff, 1890) gen. et comb. nov., ZMB.122710. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 23 Material examined Holotype VIETNAM•drypreservedspec.;LạngSơn,ĐèoKhách,KỳCùngRiver;JuilletBilletleg.;MNHNIM-2000-4486. Fig. 13. Shells and operculum of Bakyietaia duchieri (Fischer, 1898) gen. et comb. nov. A–B. Holotype, MNHN-IM-2000-4486 (http://coldb.mnhn.fr/catalognumber/mnhn/im/2000-4486, credit: MNHN-BrabantD.-2005),ĐèoKhách,LạngSơn,Vietnam.C–D. SMF.48146, Tonkin, Vietnam. E–L. KIZ.240049–240050, Longzhou, Guangxi, China. M–N. Operculum of KIZ.240049. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum M–N. European Journal of Taxonomy 1005: 1–64 (2025) 24 Other material CHINA•2specs(preservedinethanol);Guangxi,ChongzuoCity,LongzhouCounty,ShuikouTown, Poliu Village, Shuikou River, 0.5 m deep on mud substrate; 4 Mar. 2023; KIZ.240049, KIZ.240050. VIETNAM•1spec.(preserveddry);“Tonkin”(Hanoi);O.v.Möllendorffleg.;SMF.48146 Description Adult shell (Fig. 13A–K) large (32.88 ± 1.00 mm), thick, sturdy, conical, olive to olive brown, with sixwhorls,apexacute;teleoconchwhorlsslightlyinflated,withthreesmoothprimarykeels,withone totwoweakersmoothsecondarykeelslocatedbetweensutureandfirstkeel,sometimesoneadditional weakkeellocatedbetweenfirstandsecond/secondandthirdkeels,baseofshellwithonetothreeweak keels, all keels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white or orange red, adult columellar lip recurved, sometimes forming a narrow to wide crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 13M–N) corneous, ovate, relatively thick, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radula currently unknown. Remarks The newly collected specimens in Longzhou of China have a shell that is very similar to that of the holotype, and the collecting site is close to the type locality on the same river basin. Bakyietaia duchieri can be easily distinguished from the other species of Bakyietaia gen. nov. based on its large sturdy shell andinflatedbodywhorlwithshoulder.TherecommendedChinesenameis杜氏越田螺. Habitat and distribution Sand substrate and rocks in the shallow water of rivers and lakes of Western Guangxi, China and Northern Vietnam. Bakyietaia guangdungensis (Kobelt, 1906) gen. et comb. nov. Figs 14–15 Vivipara heudei var. guangdungensisKobelt,1906inKobelt1906–1909:124–125,pl.21figs12,14 (“Provinz Guang-dung”, Guangdong Province, China). Dactylochalamys guangdungensis – Prashad 1928: 169. Vivipara polyzonata–Yen1939:37,pl.3figs14–15[nonVivipara polyzonata Frauenfeld, 1862]. Angulyagra guangdungensis – Yen 1943: 128. Sinotaia polyzonata–Zilch1955:77,fig.52.—Qianet al. 2014 [non Vivipara polyzonata Frauenfeld, 1862]. Taia polyzonata – Johnson 1973: 120, 122. — Palmieri et al. 1980: 40. — Ng 1992: 125. — Chan 1996: 184–185,fig.2.—Maassen2001:44.—Clementset al. 2006: 144. — Tan & Woo 2010: 26. — Yeo & Chia 2010: 32. — Tan et al. 2012: 133 [non Frauenfeld 1862]. Viviparus polyzonata – Ng et al. 1993: 20 [non Vivipara polyzonata Frauenfeld, 1862]. Bellamya heudei guangdungensis – Shea 1994: 3–11. Sinotaia guangdungensis – Ng et al. 2014: 401–408 ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 25 Angulyagra polyzonata –Madsen&Hung2014:110,fig.2(11)[nonVivipara polyzonata Frauenfeld, 1862]. Diagnosis Shellrelativelysmall(20.87±0.93mm),whorlsinflated;columellarliprecurved,formingcallus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 28 to 29 small sharp cusps. Material examined Lectotype CHINA•drypreservedspec.;GuangdongProvince;O.v.Möllendorffleg.;designatedbyYen(1939); SMF.38890. Paralectotypes CHINA•4specs(preserveddry);GuangdongProvince;O.v.Möllendorffleg.;SMF.38822. Other material CHINA – Guangdong Province•1spec.(preserveddry);GuangzhouCity,BaiyunMountain,creeks inTaohuajianValley,mudsubstrate,onbank;25Feb.2022;Le-JiaZhangleg.;KIZ.240054•1spec. (preserved in ethanol); Qingyuan City, Lianzhou County, Xian Town; 18 Nov. 2019; bought by Hai-Ling Zhangonlocalmarket;ZMB.122693-1•3specs(preservedinethanol);ZhaoqingCity,BohaiPark, Qixing Lake, 0.1–0.2 m deep under rocks; 19 Jan. 2020; Ji-Lin Jiang leg.; ZMB.122760. – Guangxi• 4 specs (preserved in ethanol); Guilin City, Yangshuo Town; 14 Mar. 2022; bought on local market by Le-JiaZhang;ZMB.122727•2specs(preservedinethanol);LaibinCity,HeshanCounty,RenyiVillage, Huaiji Reservoir, 0.5 m deep mud substrate; 7 Jan. 2020; Ri-Bao Huang leg.; KIZ.240088. SINGAPORE•3specs(preservedinethanol);CanalatSpringleafRd;ZMB.192077. Description Adult shell (Fig. 14A–H, K–R) relatively small for the genus (20.87 ± 0.93 mm), thin but sturdy, conical, olivetoolivebrown,withfivetosixwhorls,apexacute;teleoconchwhorlsinflated,sometimeswith shoulder, with three smooth primary keels, with one to two weaker smooth secondary keels located betweensutureandfirstkeel,sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/ secondandthirdkeels,baseofshellwiththreetofiveweakkeels,allkeelsusuallydarkerthanrestof shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white or orange, adult columellar lip recurved, sometimes forming a relatively narrow crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 14I–J) corneous, ovate, relatively thin, yellow to orange; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular(Fig.15)(n=3)centraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and three to four small sharp cusps on either side; outer marginal tooth wide, almost same width as lateral tooth, with 28 to 30 small sharp cusps. European Journal of Taxonomy 1005: 1–64 (2025) 32 ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 33 Description Adult shell (Fig. 18A–AA) small to medium (25.53 ± 3.72 mm), thin to thick, sturdy, conical, olive to darkolivebrown,withfivetosixwhorls,apexacute;teleoconchwhorlssometimeswithoutshoulder, sometimesinflatedandwithshoulder,withthreesmoothprimarykeels,withonetotwoweakersmooth secondarykeelslocatedbetweensutureandfirstkeel,sometimesoneadditionalweakkeellocated betweenfirstandsecond/secondandthirdkeels,baseofshellwithtwotofiveweakkeels,allkeels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an angular periphery, columellar lip covered with thick inner shell layers, white or orange, adult columellar lip recurved, sometimes forming a rather wide crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 18AB–AG) corneous, ovate, relatively thin, yellow to orange; exterior surface smooth; interior surface with small nuclear region, around 1/4 to 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular(Fig.19)(n=6)centraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and three tofivesmallsharpcuspsoneitherside;outermarginaltoothwide,almostsamewidthaslateraltooth, with 18 to 25 small sharp cusps. Fig. 18 (preceding page). Shells and opercula of Bakyietaia wilhelmi (Yen, 1939) gen. et comb. nov. A–C. Holotype, SMF.40812, Guangdong, China. D. ZMB.122686-2, Jiangxikong, Guangdong, China. E. ZMB.122696, Heyuan, Guangdong, China. F–I. ZMB.122686-1, Jiangxikong, Guangdong, China. J. ZMB.122689, Fogang, Guangdong, China. K–L. ZMB.122688, Zhuhai, Guangdong, China. M. ZMB.122692, Shenzhen, Guangdong, China. N–O. ZMB.122685, Liuzhou, Guangxi, China. P. ZMB.122751, Zhanjiang, Guangdong, China. Q–R. ZMB.122729, Gejiu, Yunnan, China. S. ZMB.122737-3, Ledong, Hainan, China. T. ZMB.122709, Yangshan, Hainan, China. U. ZMB.114206, Ha Quang, Vietnam. V. ZMB.122770, Niuyun, Guangxi, China. W. P1010042, Niuyun, Guangxi, China. X. ZMB.122760-1, Zhaoqing, Guangdong, China. Y. YHY-BAKWIL-HS-2, Heshan, Guangxi, China. Z. 122693-2, Lianzhou, Guangdong, China. AA. ZMB.122704, Jieyang, Guangdong, China. AB–AC. Operculum of ZMB.122685. AD–AE. Operculum of ZMB.122686-1. AF–AG. Operculum of ZMB.114206. Scale bars = 1 cm, top left bar applies to all shells, separate bar for opercula AB–AG. Fig. 19. SEM photo of the radula of Bakyietaia wilhelmi (Yen, 1939) gen. et comb. nov., ZMB.122686. European Journal of Taxonomy 1005: 1–64 (2025) 34 Remarks The newly collected specimens from Qingyuan City in Guangdong have a shell that is very similar to that of the holotype. Bakyietaia wilhelmi is the most common species of this genus. It has the widest distribution range, and displays extremely high polymorphism of shell characters. This species was also found sympatrically with other species of Bakyietaia gen. nov. (B. boettgeri, B. duchieri and B. guangdungensis) in some localities (such as Qixing Lake in Zhaoqing City in Guangdong and Honghu Lake in Ledong County of Hainan). The morphotype that is similar to the holotype can be distinguished frommostcongenersbasedonitscomparativelysmallconicalshellwithnon-inflatedwhorlsand moderately keeled suture. However, some morphotypes cannot be distinguished from Bakyietaia guangdungensis based on their shell morphology. The COI tree supports the status of B. wilhelmi and B. guangdungensis as distinct species that are quite distantly related. In addition, B. wilhelmi always has fewer small cusps on the outer marginal teeth than B. guangdungensis (18–25 vs 28–30). DNA barcoding is considered necessary to unambiguously differentiate B. wilhelmi and B. guangdungensis. The recommended Chinese name is 威廉越田螺. Habitat and distribution Mud, sand and rock substrate in the shallow water of rivers, wetlands and lakes in Guangdong, Hainan, Guangxi and southern Yunnan Province, China and northern Vietnam. Introduced into Chengdu City, Sichuan Province, China and northern Borneo, Malaysia. Bakyietaia chenghuang Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:24C0929E-836B-4AC5-9829-294C4C6345B4 Figs 20–21 Diagnosis Shell medium in size (23.70 ± 5.37 mm), rounded and thin, teleoconch with weak primary keels; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 15 to 16 small sharp cusps. Etymology ‘Cheng Huang’ means ‘city god’ in Chinese, referring to the type locality in Chenghuang Town. Formed as a noun in apposition. The recommended Chinese name is 城隍越田螺. Material examined Holotype CHINA•spec.preservedinethanol;Guangxi,YulinCity,ChenghuangTown,arivernearShirentou Mountain, 0.5 m deep on rock; 13 Mar. 2022; Le-Jia Zhang leg.; KIZ.240001. Paratypes CHINA•4specs(preservedinethanol);samedataasforholotype;KIZ.240002toKIZ.240005•2specs (preservedinethanol);samedataasforholotype;ZMB.122722-1•4specs(preservedinethanol);same data as for holotype; KIZ.240089. Other material 1 spec. (preserved dry); same data as for holotype; YHY-BAKCHE-CH-1. Description Adult shell (Fig. 20A–E, H–J) medium in size (23.70 ± 5.37 mm), thin but sturdy, broadly conical or rounded,olivetoolivebrown,withfivewhorls,apexacute;teleoconchwhorlsinflated,withthreeweak, ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 35 smoothprimarykeels,withonetotwoweakersmoothsecondarykeellocatedbetweensutureandfirst keel,sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels, baseofshellwiththreetofiveweakkeels;apertureovate,large,aroundhalfofshellinheight,inner Fig. 20. Shells and operculum of Bakyietaia chenghuang Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240001, Chenghuang Town, Guangxi, China. E. Paratype, ZMB.122722-1, Chenghuang Town, Guangxi, China. F–G. Operculum of KIZ.240002. H–J. YHY-BAKCHE-CH-1, Chenghuang Town, Guangxi, China. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum F–G. European Journal of Taxonomy 1005: 1–64 (2025) 36 shell surface bluish white to purple white, outer lip thin, always with a relatively rounded periphery, columellar lip covered with thick inner shell layers, always white, adult columellar lip recurved, forming a very narrow crescent-shaped callus or without this structure, columellar lip or this structure completely covering umbilicus. Operculum (Fig. 20F–G) corneous, ovate, thin, yellow; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins. Radular(Fig.21)(n=2)centraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half width of lateral tooth, with one broad central denticle and three small sharp cusps on either side; outer marginal tooth wide, almost same width as lateral tooth, with 15 to 16 small sharp cusps. Remarks Bakyietaia chenghuang gen. et sp. nov. can be easily distinguished from most congeners based on its thin, rounded shell with a wide aperture and a very small operculum. It can be differentiated from the morphologically similar species Bakyietaia subcostata based on the smaller number of small cusps on outer marginal teeth of the radula (15–16 vs 29–43). Habitat and distribution Only known from the type locality in Guangxi, China, where it occurs on rocky substrates in the shallow water. Bakyietaia jingweiae Yen, Zhang & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:7D19E72D-8C68-4AB8-A41B-70CA77A28C0C Figs 22–23 Diagnosis Shellsmalltomediuminsize(26.79±5.37mm),sturdy,conical,whorlsnotinflated,prominentkeel above suture; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/4 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 26–28 small sharp cusps; distributed in northernVietnam, across the border in western Guangxi and in western Hainan Island, China. Fig. 21. SEM photo of the radula of Bakyietaia chenghuang Zhang, Yen & von Rintelen gen. et sp. nov., paratype, ZMB.122722-1. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 37 Etymology Named after ‘Jingwei’, a Chinese mythical bird into which the Flame Emperor Yandi’s daughter Nüwa, whodrownedinthesea,wastransformed,andwhichtriedtofillupthesea.TherecommendedChinese name is 精卫越田螺. Material examined Holotype CHINA•spec.preservedinethanol;Guangxi,BaiseCity,JingxiCounty,XinjingTown,Longtan Wetland, 0.1 m on rock; 30 Dec. 2019; Hua-Pu Huang leg.; KIZ.240006. Paratypes CHINA – Guangxi•4specs(preservedinethanol);samedataasforholotype;KIZ.240056to KIZ.240059•5specs.(preservedinethanol);samedataasforholotype;ZMB.122701•1spec. (preserved in ethanol); Guangxi, Baise City, creek near Nawang Village, 0.1 m deep on sand or rock substrate; 20 Mar. 2022; Le-Jia Zhang leg.; KIZ.240007. – Hainan Province•3specs(preservedin ethanol); Ledong Li Autonomous County, Honghu Village, Honghu Lake, 0.1 m deep sand substrate; 9Mar.2022;Le-JiaZhangleg.;ZMB.122737-1,ZMB.122737-2,ZMB.122737-4•1spec.(preservedin ethanol); Changjiang Li Autonomous County, Changhua Town, Sanjia Village, Changhua River, 0.5 m deep on rock; 9 Mar. 2022; Le-Jia Zhang leg.; KIZ.240008. VIETNAM • 4 specs (preserved in ethanol); Cao Bang, river Sông Bằng; 2000; IEBR leg.; MZMB.114431•3specs(preservedinethanol);CaRiverdrainage,Ho-Chi-Minh-Highwaybetween YenCatandTháiHòa,NghêAn;21–31Oct.2006;FrankKöhlerleg.;ZMB.114407•2specs(preserved inethanol);BaBeLakes,BacKan;2001;IEBRleg.;ZMB.114430•10specs(preservedinethanol);Ba Be Lakes, Bac Kan, ferry port; 21 Mar. 2006; Frank Köhler leg.; ZMB.114189. Other material CHINA•3specs(preserveddry);samedataasforholotype;YHY-BAKDUC-JX-1,YHY-BAKDUCJX-10, YHY-BAKDUC-JX-15. Description Adult shell (Fig. 22A–N) small to medium (26.79 ± 5.37 mm), thin to thick, sturdy, conical, olive to olivebrown,withfivetosixwhorls,apexacute;teleoconchwhorlsslightlyinflated,withthreesmooth primarykeels,withonetotwoweakersmoothsecondarykeelslocatedbetweensutureandfirstkeel, sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels,baseof shell with one to three weak keels, all keels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with a strong angular periphery, columellar lip covered with thick inner shell layers, white or orange-red, adult columellar lip recurved, sometimes forming a narrow to wide crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 22O–P) corneous, ovate, relatively thick, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/4 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular (Fig. 23) (n = 4) central tooth with one broad central denticle and four to six small sharp cusps oneitherside;lateraltoothwithonebroadcentraldenticleandfivetosixsmallsharpcuspsoneither side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle andfourtofivesmallsharpcuspsoneitherside;outermarginaltoothwide,almostsamewidthaslateral tooth, with 26 to 28 small sharp cusps. European Journal of Taxonomy 1005: 1–64 (2025) 38 Fig. 22. Shells and operculum of Bakyietaia jingweiae Yen, Zhang & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240006, Jingxi, Guangxi, China. E. Paratype, KIZ.240007, Nawang, Guangxi, China. F–H. Paratypes, ZMB.122737-1, ZMB.122737-2, ZMB.122737-4, Ledong, Hainan, China. I. Paratype, ZMB.114407,NghêAn,Vietnam.J. Paratype, KIZ.240008, Changhua, Hainan, China. K–L. Paratype, ZMB.114189, Ba Be Lakes, Bac Kan, Vietnam. M–N. Paratypes, ZMB.114430, Ba Be Lakes, Bac Kan, Vietnam. O–P. Operculum of ZMB.122701. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum O–P. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 39 Remarks Bakyietaia jingweiae gen. et sp. nov. is most similar to Bakyietaia boettgeri based on shell morphology, but differs in possessing a smaller shell and greater number of small cusps on outer marginal teeth (26–28 vs 23–24). The distribution areas of these two species are close to each other but not overlapping near the border between Guangxi, China and Vietnam. Habitat and distribution Sand substrate and rocks in the shallow water of rivers and lakes of western Guangxi and western Hainan Province, China and northern Vietnam. Bakyietaia liusanjieae Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:16B296D0-9634-4460-B0EB-770DB94244DD Figs 24–25 Diagnosis Shellmediuminsize(25.69±3.35mm),sturdy,conicalshellwithlowerspire,whorlsnotinflated; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/4 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 26–27 small sharp cusps; distributed in northern Guangxi, China. Etymology Named after ‘Liu Sanjie’ (刘三姐, Liu family’s third daughter), a legendary folk singer of the Zhuang people in Guangxi. The type locality of this species is close to her hometown. The recommended Chinese name is 歌仙越田螺. Material examined Holotype CHINA•spec.preservedinethanol;Guangxi,HechiCity,LuochengMulaoAutonomousCounty,near Hemu Town, river in Xinhui Village, 0.5 m deep on dam; 16 Mar. 2022; Le-Jia Zhang leg.; KIZ.240009. Paratypes CHINA – Guangxi•2specs(preservedinethanol);samedataasforholotype;KIZ.240010,KIZ.240011 •2specs(preservedinethanol);samedataasforholotype;ZMB.122722-2•2specs(preserveddry); Fig. 23. SEM photo of the radula of Bakyietaia jingweiae Yen, Zhang & von Rintelen gen. et sp. nov., ZMB.122701. European Journal of Taxonomy 1005: 1–64 (2025) 40 Fig. 24. Shells and operculum of Bakyietaia liusanjieae Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240009, Xinhui, Guangxi, China. E. Paratype, KIZ.240092, Liusanjie Town, Guangxi, China. F–G. Paratypes, KIZ.240010, KIZ.240011, Xinhui, Guangxi, China. H. YHY-BAKLIUXH-1 Xinhui, Guangxi, China. I–J. Paratype, ZMB.122722-2, Baishou, Guangxi, China. K. Paratype, ZMB.122763, Hezhou, Guangxi, China. L–M. Operculum of paratype KIZ.240010. N–O. Operculum of ZMB.122722-2. Scale bars = 1 cm, top left bar applies to all shells, separate bar for opercula L–O. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 41 samedataasforholotype;KIZ.240090•2specs(preservedinethanol);GuilinCity,BaishouTown, Baishou River, 0.5 m deep on mud and sand substrate; 15 Mar. 2022; Le-Jia Zhang leg.; KIZ.240012, KIZ.240013•2specs(preservedinethanol);samedataasforpreceding;ZMB.122738•1spec.;same dataasforpreceding;KIZ.240091•1spec.(preserveddry);HechiCity,YizhouDistrict,Liusanjie Town,onbankofXiajianRiver;16Mar.2022;Le-JiaZhangleg.;KIZ.240092•2specs(preserveddry); samedataasforpreceding;17Mar.2022;KIZ.240093•2specs(preservedinethanol);HezhouCity, Zhongshan County, Tonggu Town, Fengzhen Village, Shangpu, 0.5 m deep on mud substrate in a pond; 9Mar.2020;Shui-YangHuangleg.;KIZ.240014,KIZ.240015•1spec.(preservedinethanol);same data as for preceding; ZMB.122763. Other material CHINA•1spec.(preserveddry);samedataasforholotype;YHY-BAKLIU-XH-1. Description Adult shell (Fig. 24A–K) medium in size (25.69 ± 3.35 mm), thin but sturdy, conical shell with low spire,olivetoolivebrown,withfivetosixwhorls,apexacute;teleoconchwhorlsnotinflated,withthree smooth relatively weak primary keels, with one to two even weaker smooth secondary keels located betweensutureandfirstkeel,sometimesoneadditionalweakkeellocatedbetweenfirstandsecond/ secondandthirdkeels,baseofshellwithonetofiveweakkeels,allkeelsusuallydarkerthanrestof shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, orangered or dark purple, outer lip thin, always with a strong basal angular periphery, columellar lip covered with thick inner shell layers, white or orange red, adult columellar lip recurved, sometimes forming a relatively wide crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 24L–O) corneous, ovate, relatively thick, dark orange to dark red; exterior surface smooth; interior surface with small nuclear region, around 1/4 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular (Fig. 25) (n = 3) central tooth with one broad central denticle and three to four small sharp cusps on either side; lateral tooth with one broad central denticle and two to three small sharp cusps on either side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and fivesmallsharpcuspsoneitherside;outermarginaltoothwide,almostsameaslateraltoothinwidth, with 26 to 27 small sharp cusps. Fig. 25. SEM photo of the radula of Bakyietaia liusanjieae Zhang, Yen & von Rintelen gen. et sp. nov., ZMB.122722-2. European Journal of Taxonomy 1005: 1–64 (2025) 48 Etymology Named after ‘Lui Kong’, the god of thunder in the local Min Nan Chinese dialect, popular in the folklore of Leizhou County which includes the type locality of this species. The recommended Chinese name is 雷神越田螺. Material examined Holotype CHINA•spec.preservedinethanol;GuangdongProvince,ZhanjiangCity,LeizhouCounty,Liren Village, near Nanguang Farm Second Team, 0.1–0.5 m deep on mud and rock substrate in ponds; 6 Apr. 2020; Yu-Xuan Zhou leg.; KIZ.240037. Paratypes CHINA•4specs(preservedinethanol);samedataasforholotype;KIZ.240038toKIZ.240041•2specs (preservedinethanol);samedataasforholotype;ZMB.122764•3specs(preservedinethanol);same data as for holotype; KIZ.240101. Other material CHINA•1spec.(preserveddry);samedataasforholotype;YHY-BAKLK-LR-1. Fig. 30. Shells and operculum of Bakyietaia luikongi Yen, Zhang & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240037, Leizhou, Guangdong, China. E–F. Paratype, ZMB.122764, Leizhou, Guangdong, China. G. YHY-BAKLK-LR-1, Leizhou, Guangdong, China. H–I. Operculum of holotype, KIZ.240037. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum G–H. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 49 Description Adult shell (Fig. 30A–G) relatively small for the genus (20.66 ± 0.70 mm), thin but sturdy, broad conical toconical,darkolivebrown,withfivewhorls,apexacute;teleoconchwhorlssometimeswithshoulder, with three weak but obvious smooth primary keels, with one to two weaker smooth secondary keels locatedbetweensutureandfirstkeel,alwayswithoneweakkeellocatedbetweenfirstandsecond/second and third keels, base of shell with three to four weak keels, all keels usually darker than rest of shell surface; aperture ovate, lnearly half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thin inner shell layers, white to orange, columellar lip folded outwards, completely covering umbilicus. Operculum (Fig. 30H–I) corneous, ovate, thin, dark orange to dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular (Fig. 31) (n = 2) central tooth with one broad central denticle and four small sharp cusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and three to four small sharp cusps on either side; outer marginal tooth wide, almost same width as lateral tooth, with 19 to 20 small sharp cusps. Remarks Bakyietaia luikongi gen. et sp. nov. is the only species of Bakyietaia gen. nov. with a conical shell and weak primary keels distributed outside Hainan Island and is the sister species of the clade including all species with weak primary keels from Hainan. It can be easily distinguished from all congeners based on the small thin conical shell with three very weak primary keels and lower spire. It is the smallest species among those with weak primary keels. Habitat and distribution Only known from mud and rock substrate in the shallow water of ponds in Leizhou Peninsula, Guangdong Province, China. Fig. 31. SEM photo of the radula of Bakyietaia luikongi Yen, Zhang & von Rintelen gen. et sp. nov., paratype, ZMB.122764. European Journal of Taxonomy 1005: 1–64 (2025) 50 Bakyietaia fontinalis Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:8DFECB0B-656C-42B6-B3FE-51C2BC907619 Figs 32–33 Diagnosis Shellmediuminsize(24.25±2.59mm),sturdy,conical,whorlsnotinflated,withweakprimarykeels, shoulder rounded; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 26–29 small sharp cusps. Etymology Refers to the cold spring habitat of the type locality. The recommended Chinese name is 冷泉越田螺. Material examined Holotype CHINA•spec.preservedinethanol;HainanProvince,DinganCounty,JiuwentangTown,Jiuwentang Cold Spring, 0.5 m deep on mud and sand substrate; 6 Mar. 2022; Le-Jia Zhang leg.; KIZ.240042. Fig. 32. Shells and operculum of Bakyietaia fontinalis Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240042, Jiuwentang, Hainan, China. E. YHY-BAKFON-LQ-1, Jiuwentang, Hainan, China. F. Paratype, ZMB.122764, Jiuwentang, Hainan, China. G. Paratype, KIZ.240104, Wanquan River, Hainan, China. H–I. Operculum of holotype, KIZ.240042. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum H–I. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 51 Paratypes CHINA•1spec.(preservedinethanol);samedataasforholotype;KIZ.240043•2specs(preserved inethanol);samedataasforholotype;ZMB.122733•1spec.(preservedinethanol);samedataasfor holotype;KIZ.240102•2specs(preservedinethanol);HainanProvince,DinganCounty,rivernear LeimingTown;2018;KIZ.240103•1spec.(preservedinethanol);HainanProvince,QionghaiCity, Shibi Town, Wanquan River, 0.1 m deep on rock; 7 Mar. 2022; Le-Jia Zhang leg., KIZ.240104. Other material CHINA•1spec.(preserveddry);samedataasforholotype;YHY-BAKFON-LQ-1. Description Adult shell (Fig. 32A–G) medium in size (24.25 ± 2.59 mm), thin to thick, sturdy, conical, olive to dark olivebrown,withfivewhorls,apexacute;teleoconchwhorlsnotinflated,withthreeweakbutobvious smoothprimarykeels,withonetotwoweakersmoothsecondarykeellocatedbetweensutureandfirst keel,alwayswithoneadditionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels,base of shell with two to four weak keels, all keels usually darker than the other part of shell surface in colour; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with a strong angular periphery, columellar lip covered with thick inner shell layers, white or orange, adult columellar lip recurved, sometimes forming a crescent-shaped callus, this structure or columellar lip completely covering umbilicus. Operculum (Fig. 32H–I) corneous, ovate, thin, orange to dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular(Fig.33)(n=2)centraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half width of lateral tooth, with one broad central denticle and four tofivesmallsharpcuspsoneitherside;outermarginaltoothwide,almostsameaslateraltoothinwidth, with 26 to 29 small sharp cusps. Remarks Bakyietaia fontinalis gen. et sp. nov. is one of the species of Bakyietaia gen. nov. with weak primary keels. This species can be easily distinguished from all congeners, especially the morphologically similar Fig. 33. SEM photo of the radula of Bakyietaia fontinalis Zhang, Yen & von Rintelen gen. et sp. nov., paratype, ZMB.122733. European Journal of Taxonomy 1005: 1–64 (2025) 52 species B. mutica,basedonitsmedium-sizedconicalshellwithwhorlsnotinflated,roundedshoulder and more cusps on the outer marginal teeth (26–29 vs 19–24). Habitat and distribution Mud and rock substrate in the shallow water of springs and rivers of central-eastern Hainan Province, China. Bakyietaia naiadica Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:1E34D07F-05C1-4819-ADC6-D02399C18B8B Figs 34–35 Diagnosis Shell medium in size (25.73 ± 0.62 mm), sturdy, cylindrical outline, with very weak primary keels, weak keel above suture, outer lip angular; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 19–22 small sharp cusps. Etymology Named after Naiads, the nymphs of freshwater bodies such as springs in Greek mythology. The recommended Chinese name is 龙婆越田螺. Fig. 34. Shells and operculum of Bakyietaia naiadica Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240044, Longpo Temple, Hainan, China. E. Paratype, KIZ.240045, Xue Village, Hainan, China. F–G. YHY-BAKNAI-XC-1, Xue Village, Hainan, China. H–I. Operculum of holotype, KIZ.240044. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum F–G. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 53 Material examined Holotype CHINA•spec.preservedinethanol;HainanProvince,HaikouCity,springnearLongpoTemple,0.1m deep on rock; 5 Mar. 2022; Le-Jia Zhang leg.; KIZ.240044. Paratypes CHINA•1spec.(preservedinethanol);samedataasforholotype;ZMB.122743•1spec.(preservedin ethanol); Hainan Province, wetland in Xue Village, Haikou City, 0.1 m deep on rock substrate; 3 May 2022; Le-Jia Zhang leg.; KIZ.240045. Other material CHINA•1spec.(preserveddry);HainanProvince,wetlandinXueVillage,HaikouCity,0.1mdeepon rock substrate; 3 May 2022; Le-Jia Zhang leg.; YHY-BAKNAI-XC-1. Description Adult shell (Fig. 34A–G) medium (25.73 ± 0.62 mm), thin but sturdy, conical, olive to dark olive brown, withfivewhorls;teleoconchwhorlsinflated,withshoulder,withthreeveryweaksmoothprimarykeels, withonetotwoevenweakersmoothsecondarykeelslocatedbetweensutureandfirstkeel,sometimes withoneadditionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels,baseofshellwith two to four weak keels, all keels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white or pale orange, adult columellar lip recurved, sometimes forming a crescent-shaped callus, this structure completely covering umbilicus. Operculum (Fig. 34H–I) corneous, ovate, thin, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. Radular(Fig.35)(n=1)centraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcusps oneitherside;lateraltoothwithonebroadcentraldenticleandfourtofivesmallsharpcuspsoneither side; inner marginal tooth narrow, about half width of lateral tooth, with one broad central denticle and fivetosixsmallsharpcuspsoneitherside;outermarginaltoothwide,almostsameaslateraltoothin width, with 19 to 22 small sharp cusps. Fig. 35. SEM photo of the radula of Bakyietaia naiadica Zhang, Yen & von Rintelen gen. et sp. nov., paratype, ZMB.122743. European Journal of Taxonomy 1005: 1–64 (2025) 54 Remarks Bakyietaia naiadica gen. et sp. nov. can be easily distinguished from all congeners, especially the morphologically similar B. mutica, based on its more cylindrical shell with weaker primary keels and less prominent keel at suture. Habitat and distribution Rock substrate in the shallow water of springs and wetlands of northern Hainan Province, China. Bakyietaia luuemxlong Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:3C33CDFF-1DD8-4AC2-A4D6-A28D0535B1A4 Figs 36–37 Diagnosis Shellsmalltomediuminsize(23.56±2.58mm),sturdy,whorlsinflated,withweakprimarykeels, moderate keel above suture; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 20 small sharp cusps; distributed in southern Hainan Island. Etymology According to the mythology of the Hlai people of Hainan Island, ‘luuemx long’, which means ‘forget to grow up’ in the Hlai language, is a race of dwarves living in the forest. Formed as a noun in apposition. The recommended Chinese name is 阑咙越田螺. Material examined Holotype CHINA•spec.preservedinethanol;HainanProvince,QionghaiCity,HuishanTown,creeksnear farmland of Mutang Village, 0.1 m deep on mud substrate; 7 Mar. 2022; Le-Jia Zhang leg.; KIZ.240046. Paratypes CHINA•2specs(preservedinethanol);samedataasforholotype;KIZ.240047–240048•1spec. (preserved in ethanol); same data as for holotype; ZMB.122739. Other material CHINA•1spec.(preserveddry);samedataasforholotype;YHY-BAKLUU-MT-1. Description Adult shell (Fig. 36A–E, H–J) small to medium (23.56 ± 2.58 mm), thin but sturdy, conical, dark olive brown,withfivewhorls;teleoconchwhorlsinflated,withthreeweakbutobviousprimarykeels,with onetotwoevenweakersmoothsecondarykeelslocatedbetweensutureandfirstkeel,alwayswithone additionalweakkeellocatedbetweenfirstandsecond/secondandthirdkeels,baseofshellwithtwoto four weak keels, all keels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white, columellar lip folded outwards, covering umbilicus. Operculum (Fig. 36F–G) corneous, ovate, thin, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 55 Fig. 36. Shells and operculum of Bakyietaia luuemxlong Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Holotype, KIZ.240046, Mutang, Hainan, China. E. Paratype, ZMB.122739, Mutang, Hainan, China. F–G. Operculum of holotype, KIZ.240046. H–J. YHY-BAKLUU-MT-1, Mutang, Hainan, China. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum F–G. European Journal of Taxonomy 1005: 1–64 (2025) 56 Radular (Fig. 37) (n = 1) central tooth with one broad central denticle and four small sharp cusps on either side; lateral tooth with one broad central denticle and three small sharp cusps on either side; inner marginal tooth narrow, about half of lateral tooth in width, with one broad central denticle and unknown number of small sharp cusps on either side (all heavily worn); outer marginal tooth wide, almost same as lateral tooth in width, with around 20 small sharp cusps. Remarks Bakyietaia luuemxlong gen. et sp. nov. is one of the species of Bakyietaia gen. nov. with weak primary keels. This species can be easily distinguished from all congeners based on the smallto medium-sized conicalshellwithinflatedwhorlsandmoderatekeelabovesuture. Habitat and distribution Only known from the type locality on mud substrate in the shallow water of creeks in southern Hainan Province, China. Bakyietaia indrapura Zhang, Yen & von Rintelen gen. et sp. nov. urn:lsid:zoobank.org:act:D7B758FD-46BD-4DED-8C15-AD9BED3528AA Figs 38–39 Diagnosis Shellmediuminsize(26.92±2.45mm),thin,sturdy,whorlsinflated,withprominentprimarykeelsat suture; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins; outer marginal tooth of radula with 21–26 small sharp cusps; distributed in central Vietnam. Etymology Named after Indrapura, capital of the ancient kingdom of Champa, which is close to the type locality. Formed as a noun in apposition. The recommended Chinese name is 占婆越田螺. Material examined Holotype VIETNAM•1spec.(preservedinethanol);PhuocSon,KhamDuc,CaiRiverdrainage;21–31Oct. 2006; Frank Köhler leg.; ZMB.114403.1. Fig. 37. SEM photo of the radula of Bakyietaia luuemxlong Zhang, Yen & von Rintelen gen. et sp. nov., paratype, ZMB.122739. ZHANG L.-J. et al., New genus of Viviparidae (Mollusca) from South China 57 Paratypes VIETNAM•2specs(preservedinethanol);samedataasforholotype;ZMB.114403•5specs(preserved inethanol);NghêAn,TânDuongDistrict,TamQuang,TruongSonMts,mountaincreek;21–31Oct. 2006;FrankKöhlerleg.;ZMB.114402.1,ZMB.114402•3specs(preservedinethanol); same data as for preceding; ZMB.114406. Description Adult shell (Fig. 38A–F) medium in size (26.92 ± 2.45 mm), thin but sturdy, conical, olive to greenish brown,withfivetosixwhorls,apexacute;teleoconchwhorls,especiallybodywhorl,slightlyinflated, sometimes forming shoulder, with three smooth primary keels, with one to two weaker smooth secondary keelslocatedbetweensutureandfirstkeel,sometimesoneadditionalweakkeellocatedbetweenfirstand second/secondandthirdkeels,baseofshellwiththreetofiveweakkeels,keelsusuallydarkerthanrest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with a strong angular periphery, columellar lip covered with thick inner shell layers, white or orange, adult columellar lip recurved, forming a very narrow crescent-shaped callus or without this structure, columellar lip or this structure usually covering umbilicus, umbilicus sometimes narrowly open, bordered by a keel. Operculum (Fig. 38G–H) corneous, ovate, thin, yellow to orange; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins. Fig. 38. Shells and operculum of Bakyietaia indrapura Zhang, Yen & von Rintelen gen. et sp. nov. A–D. Paratype, ZMB.114402.1, Nghe An, Vietnam. E–F. Holotype, ZMB.114403, Phuoc Son, Vietnam. K–L. Operculum of paratype ZMB.114402. Scale bars = 1 cm, top left bar applies to all shells, separate bar for operculum G–H. European Journal of Taxonomy 1005: 1–64 (2025) 64 Zhang L.J. & von Rintelen T. 2021. The neglected operculum: A revision of the opercular characters in river snails (Caenogastropoda: Viviparidae). Journal of Molluscan Studies 87: eyab008. https://doi.org/10.1093/mollus/eyab008 Zhang L.J., Chen S.C., Yang L.T., Jin L. & Köhler F. 2015. Systematic revision of the freshwater snail Margarya Nevill, 1877 (Mollusca: Viviparidae) endemic to the ancient lakes of Yunnan, China, with description of new taxa. Zoological Journal of the Linnean Society 174: 760–800. https://doi.org/10.1111/zoj.12260 Zhang L.J., Du L.N. & von Rintelen T. 2023. A new genus of river snails, Dalipaludina (Gastropoda, Viviparidae), endemic to the Yunnan Plateau of SW China. Zoosystematics and Evolution 99: 285–297. https://doi.org/10.3897/zse.99.102586 Zhu X.G. 1994. Jurassic-Cretaceous nonmarine gastropods from northern Xinjiang. Acta Palaeontologica Sinica 33: 85–105. Zilch A. 1938. Das Vorkommen von Buliminopsis incerta (Pfr.) auf Formosa und in China. Archiv für Molluskenkunde 7: 3. Zilch A. 1955. Die Typen und Typoide des Natur-Museums Senckenberg, 14: Mollusca, Viviparidae. Archiv für Molluskenkunde 84: 45–87. Zilch A. 1974. Zur Geschichte der deutschen Malakozoologie, XIV. Vinzenz Gredler und die Erforschung der Weichtiere Chinas durch Franziskaner aus Tirol. Archiv für Molluskenkunde 104: 171–228. Printed versions of all papers are deposited in the libraries of four of the institutes that are members of the EJTconsortium:MuséumnationaldʼHistoirenaturelle,Paris,France;MeiseBotanicGarden,Belgium; Royal Museum for Central Africa, Tervuren, Belgium; Royal Belgian Institute of Natural Sciences, Brussels, Belgium. The other members of the consortium are: Natural History Museum of Denmark, Copenhagen, Denmark; Naturalis Biodiversity Center, Leiden, the Netherlands; Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain; Leibniz Institute for the Analysis of Biodiversity Change, Bonn – Hamburg, Germany; National Museum of the Czech Republic, Prague, Czech Republic; The Steinhardt Museum of Natural History, Tel Aviv, Israël. Supplementary files Supp. file 1. The alignment of the COI sequences in the present study. https://doi.org/10.5852/ejt.2025.1005.2985.13431 Supp. file 2. ML tree based on the COI sequences in the present study https://doi.org/10.5852/ejt.2025.1005.2985.13433