Zoosyst. Evol. 100 (4) 2024, 1201-1209 | DOI 10.3897/zse.100.130676 > PENSUFT. Gee Ee BERLIN A new species of Petraeomastus MOllendorff, 1901, with an atypical shell morphology from the Lancangjiang River Valley in southwest China (Gastropoda, Stylommatophora, Enidae) Zhong-Guang Chen**, Yu-Ting Dai!", Xiao-Ping Wu’, Jiao Jiang*, Shan Ouyang! 1 School of Life Sciences, Nanchang University, Nanchang 330031, China 2 Zhejiang Museum of Natural History, Hangzhou, Zhejiang 310012, China https://zoobank. org/997F DAB6-DF4D-45C3-A53C-29C1BOID709E Corresponding authors: Jiao Jiang (149152414@qq.com); Shan Ouyang (ouys1963@qq.com) Academic editor: Frank Kohler # Received 27 June 2024 # Accepted 6 August 2024 Published 29 August 2024 Abstract Our study contains the first molecular phylogeny of Chinese enids based on the mitochondrial markers cytochrome oxidase c (CO/) and 16S rRNA (/6S). We have sequenced 19 species belonging to 10 out of the 12 currently accepted genera. A new species, Petrae- omastus limenghuai Chen, Dai, Wu & Ouyang, sp. nov., is described from the Lancangjiang River Valley in southwest China based on comparative morphology and molecular phylogeny. The currently accepted classification of Chinese enids relies largely on shell morphology and is deemed to require systematic revision. Key Words Biodiversity, dry-hot river valley, land snails, phylogeny, taxonomy Introduction Enidae Woodward, 1913, encompasses small to large species from Eurasia, northern Africa, and northern Aus- tralia (Wu 2018). China represents a diversity hotspot of the family, harboring about 185 described species and subspecies (Heude 1882, 1885; Ancey 1883, 1884: Hil- ber 1883; Mollendorff 1901; Annandale 1923; Yen 1938, 1939; Chen and Zhang 2000, 2001; Wu and Wu 2009; Wu and Zheng 2009; Wu and Gao 2010; Zhang et al. 2010; Wang and Wu 2012; Wu and Fang 2012; Wu and Xu 2012; Fang and Wu 2013; Wang and Wu 2013; Wu and Xu 2013; Wu 2018; Chen 2020; Chen et al. 2024a, 2024b). To date, all taxonomic studies have been based exclusively on morphology, with no molecular genetic data being available (Wu 2018; Chen 2020; Chen et al. * These authors contributed equally to this work. 2024a, 2024b). Several Chinese genera as currently delin- eated exhibit overlapping morphological characteristics, hampering an unambiguous classification. The distribu- tion of Enidae in China is highly uneven, with most spe- cies restricted to dry-hot sections of several river valleys in the southwest (Wu 2018), including the Bailongjiang River Valley, the Fujiang River Valley, the Minjiang Riv- er Valley, the Daduhe River Valley, the Jinshajiang River Valley, and the Lancangjiang River Valley. Among these valleys, the Lancangjiang River Valley is one of the most remote and poorly studied. There has been almost no sub- sequent study after several species were described from here in the late 19" to early 20" centuries (Heude 1882; Ancey 1883; Hilber 1883; Ancey 1884; Heude 1885; Annandale 1923). The species composition of a large sec- tion of the Lancangjiang River Valley is still unclear. Copyright Chen, Z.-G. et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 1202 During land snail surveys in 2023, we discovered a group of enid specimens with ribbed shells from the Lan- cangjiang River Valley that did not resemble any known species and were challenging to place in any genus. Based on a combination of comparative morphology and mo- lecular phylogenetic analysis, we describe these snails as a new species of the genus Petraeomastus Mollendorff, 1901. The discovery contributes to our understanding of the morphological variations within Petraeomastus in China, suggesting that further exploration of the species diversity of Enidae in the Lancangjiang River Valley may yield additional insights. Furthermore, the significant mor- phological variation within the same genus and the simi- lar morphology between different genera indicate that the current taxonomic classification of Chinese Enidae may be problematic, requiring an integrative, systematic revision. Materials and methods Specimens were collected from southern China in 2023. Living specimens were initially frozen at -20 °C for 12 hours and subsequently thawed at room temperature for 12 hours to facilitate the extraction of soft parts. The soft parts were then fixed with 70% ethanol. Empty shells were cleaned, dried, and preserved at 4 °C. Soft parts were transferred from 70% alcohol to 10% alcohol and softened at 4 °C for 5 hours before dissection. Photo- graphs were taken by camera and edited in Adobe Photo- shop CC 2015 (Adobe, San Jose, US). Maps were made in ArcGIS Pro (Esri, Redlands, US). Genomic DNA was extracted from foot tissues preserved in 70% ethanol using a TIANamp Marine Animals DNA Kit (Tiangen Biotech, China). The quality and concentration of the DNA were checked using 1% agarose gel electrophoresis and NanoDrop 2000 (Thermo Scientific, USA). Partial cyto- chrome c oxidase subunit 1 (COZ) and 16S ribosomal RNA (/6S) were amplified and sequenced for molecular phyloge- netic analyses. Polymerase chain reaction (PCR) systems, conditions, and primer pairs are listed in Table 1. Sequences were aligned using MEGA v. 6.0 (Tamura et al. 2013) and checked manually. The accession numbers of other species and newly obtained sequences are given in Table 2. Phylogenies reconstructed by the dataset combined two genes using maximum likelihood (ML) and Bayesian inference (BI). Camaena detianensis Zhou & Lin, 2016, Pupilla muscorum (Linnaeus, 1758), and Achatinella sowerbyana Pfeiffer, 1855, were used as the outgroups for rooting the trees. ML analyses were performed in IQ-TREE v. 1.6.12 (Minh et al. 2013) using the Ultrafast Chen, Z.-G. et al.: A new species of Petraeomastus bootstrap approach (Minh et al. 2013) with 10,000 itera- tions. The most appropriate model of sequence evolution (GTR+I+G) was selected under PartitionFinder2 v. 1.1 (Lanfear et al. 2017). Bayesian inference (BI) analysis was conducted in MrBayes v. 3.2.6 (Ronquist et al. 2012). The most appropriate model of sequence evolution (GTR+I+G) was selected under ModelFinder (Kalyaanamoorthy et al. 2017). Four simultaneous runs with four independent Mar- kov Chain Monte Carlo (MCMC) algorithms were imple- mented for 10 million generations, and trees were sampled every 10,000 generations with a burn-in of 25%. The con- vergence was checked with the average standard deviation of split frequencies <0.01 and the potential scale reduction factor (PSRF) ~ 1. Trees were visualized in FigTree v.1.4.3 (http://tree.bio.ed.ac.uk/software/figtree/). Abbreviations NCU_XPWU Laboratory of Xiao-Ping Wu, Nanchang University (Nanchang, Jiangxi, China), ZMNH Zhejiang Museum of Natural History (Hangzhou, Zhejiang, Chi- na), At atrium, AR retractor muscle of the appendicular branch, A-1 most proximal section of penial appendix, A-2 penial appendix section between and thicker than A-1 and A-3, usually bulb-shaped, A-3 section of the penial appendix connecting proximally A-2 and distally A-4, A-4 thinnest part of the penial appendix between A-5 and A-3, A-5 distal part of the penial appendix, more or less swollen, BC bursa copulatrix, BCD bursa copu- latrix duct, D diverticle of the bursa copulatrix duct, Ep epiphallus, EpC epiphallic caecum, FI flagellum, FO free oviduct, P penis, PC penial caecum, PR retractor muscle of the penial branch, Va vagina, VD vas deferens. Results Phylogenetic analyses The sequence dataset consisting of 30 CO/ and 34 16S se- quences from 19 species, including three outgroup taxa, was employed for phylogenetic analyses (Table 2). The alignments of the CO/ and /6S genes had lengths of 666 and 437 characters, respectively. Within these alignments, 289 and 231 sites were variable, and 274 and 221 sites were parsimony informative. The Bayesian and Maxi- mum Likelihood analyses produced largely consistent phylogenies (Fig. 1). The genus Pupinidius Mollendorff, 1901, is a polyphyletic group, comprising three distinct Table 1. Primer pairs and PCR conditions used in the analyses of the CO/ and /6S genes. Genes Primer pairs COl LCO1490: GGTCAACAAATCATAAAGATATT GG GGAGCTCCGGTTTGAACTCAGATC zse.pensoft.net Reaction systems 12.5 ul 2 x Taq Plus Master Mix Il (Vazyme, 94 °C: 2 min; 94 °C: 10s, HCO2198: TAAACTTCAGGGTGACCAAAAAATCA Nanjing, China), 1 pl template DNA, 1 ul of 50 °C: 60s, 72 °C: 1 min, each pair of primers, 9.5 ul ddH20 16S 16SA: CGGCCGCCTGTTTATCAAAAACAT 16SB: 12.5 ul 2 x Tag Plus Master Mix Il (Vazyme, 94 °C: 2 min; 94 °C: 10s, Nanjing, China), 1 pl template DNA, 1 pl of 50°C: 60s, 72 °C: 1 min, each pair of primers, 9.5 ul ddH20 Reference Folmer et al. 1994 Cycling conditions 35 cycles; 72 °C: 10 min Pall-Gergely et al. 2019 35 cycles; 72 °C: 10 min Zoosyst. Evol. 100 (4) 2024, 1201-1209 Table 2. Genbank accession numbers of sequences used in this paper. 1203 Species Locality Col 16S References Petraeomastus limenghuai sp. nov. 1 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945840 PP956541 This study Petraeomastus limenghuai sp. nov. 2. Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945841 PP956542 This study Petraeomastus limenghuai sp. nov. 3. Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945842 PP956543 This study Petraeomastus limenghuai sp. nov. 4 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945843 PP956544 This study P. gredleri 1 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945844 PP956545 This study P. gredleri 2 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945845 PP956546 This study P. heudeanus 1 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945846 PP956547 This study P. heudeanus 2 Rumei, Mangkang, Xizang, China, 29°36'39"N, 98°21'1"E PP945847 PP956548 This study Serina ser 1 Wenxian, Gansu, China, 33°10'33'"N, 105°0'8"E PP945822 PP956524 This study Serina ser 2 Wenxian, Gansu, China, 33°10'33"N, 105°0'8"E PP945823 PP956525 This study S. schileykoi Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945826 PP956528 This study Sesp- hl Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945824 PP956526 This study S.S).-2 Wudu, Gansu, China, 33°25'9'N, 104°48'44"E PP945825 PP956527 This study Pupinidius pupinidius 1 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945829 PP956531 This study Pupinidius pupinidius 2 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945830 PP956532 This study Pu. pupinella 1 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945827 PP956529 This study Pu. pupinella 2 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945828 PP956530 This study Pu. Sp. Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945831 PP956533 This study Pu. melinostoma 1 Wenxian, Gansu, China, 33°10'33'N, 105°0'8'E PP945832 PP956552 This study Pu. melinostoma 2 Wenxian, Gansu, China, 33°10'33"N, 105°0'8"E PP945833 PP956553 This study Pu. porrectus 1 Danba, Ganzu, China, 30°51'11'"N, 101°49'27°E PP945848 PP956549 This study Pu. porrectus 2 Danba, Ganzu, China, 30°51'11"N, 101°49'27'°E PP945849 PP956550 This study Subzebrinus dolichostoma Wenxian, Gansu, China, 33°10'33'"N, 105°0'8"E PP945832 PP956534 This study Su. beresowskii Jiuzhaigou, Sichuan, China, 33°15'51"N, 104°14'6"E =PP945833 This study Clausiliopsis szechenyi 1 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP956554 This study Clausiliopsis szechenyi 2 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP956555 This study Turanena microconus 1 Diebu, Gansu, China, 33°58'10"N, 103°31'8'E PP945834 PP956535 This study Turanena microconus 2 Diebu, Gansu, China, 33°58'10"N, 103°31'8'E PP945835 PP956536 This study Pupopsis pupopsis 1 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945836 PP956537 This study Pupopsis pupopsis 2 Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945837 PP956538 This study Mirus cantori 1 Nanjing, Jiangsu, China, 32°4'13'N, 118°51'9"E PP945838 PP956539 This study Mirus cantori 2 Nanjing, Jiangsu, China, 32°4'13'N, 118°51'9"E PP945839 PP956540 This study M. frinianus Jiangxi, China MT767366 MT767366 Unpublished Dolichena miranda 1 Maoxian, Sichuan, China, 31°46'26'"N, 103°46'45'E PP956556 This study Dolichena miranda 2 Maoxian, Sichuan, China, 31°46'26'"N, 103°46'45'E PP956557 This study Holcauchen sulcatus Wudu, Gansu, China, 33°25'9"N, 104°48'44"E PP945850 PP956551 This study Achatinella sowerbyana Hawaii KX356680 KX356680 Price et al. (2016) Pupilla muscorum Sweden KC185404 KC185404 — Unpublished Camaena detianensis Chongzuo, Guangxi, China KX345076 KX345081 ~— Ai et al. (2016) clades. The specimens with ribbed shells from the Lan- cangjiang River Valley were strongly supported as a sister taxon of Petraeomastus gredleri (Hilber, 1883) and form a monophyletic group with Petraeomastus heudeanus (Ancey, 1883), which is the type species of the genus. We describe these specimens as a new species here. The genetic distances of COI sequences between the new spe- cies and other congeners ranged from 20.5% to 23.0%. Systematics Family Enidae Woodward, 1903 Subfamily Eninae Woodward, 1903 Genus Petraeomastus MOllendorff, 1901 Type species. Buliminus heudeanus Ancey, 1883, by original designation. Petraeomastus limenghuai Chen, Dai, Wu & Ouyang, Sp. nov. https://zoobank.org/EB5041F9-7ECA-4A BO-B209-52FA3249CC3F Figs 2A, 3 Type. Holotype. 24 NCU XPWU_AN351, Rumei Town [80524], Mangkang County [1°54], Changdu City [Babi], Xizang Autonomous Region [/8je BA [X], China, 29°36'20"N, 98°20'40"E, 2838 m as.l., leg. Zhong-Guang Chen, Meng-Hua Li & Jin-Sheng Mou, August 2023. Paratypes: n = 12, 24 NCU_XPWU_AN352-65; n= 2, ZMNH-LB-240003—04, other information same as holotype. Diagnosis. Shell turreted (vs. cylindrical to conical in all congeners), teleoconch ribbed (vs. smooth in all con- geners). Flagellum long. Diverticle unexpanded. Description. Shell turreted, apex gradually point- ed; most swollen at body whorl, dextral, medium-sized, zse.pensoft.net 1204 64/0.85 92/0.92 /0.80 52/0.68 84/0.85 al 97/1 76/0.63 99/1 94/0.99 99/1 Chen, Z.-G. et al.: A new species of Petraeomastus Serina ser 1 A Serina ser 2 Serina sp. 1 Serina sp. 2 Serina schileykoi Pupinidius melinostoma 1 Pupinidius melinostoma 2 Pupinidius pupinella 1 97/1 Pupinidius pupinella 2 Pupinidius pupinidius 1 Pupinidius pupinidius 2 Pupinidius sp. 99/1 Subzebrinus dolichostoma —— Subzebrinus beresowskii Clausiliopsis szechenyi 1 * Clausiliopsis szechenyi 2 Turanena microconus 1 Turanena microconus 2 Pupopsis pupopsis 1 Pupopsis pupopsis 2 * Mirus cantori 1 aces Mirus cantori 2 Mirus frinianus Dolichena miranda 1 k Dolichena miranda 2 Petraeomastus limenghuai sp. nov. 1 7910.91 99/1 100/1 100/1 Petraeomastus limenghuai sp. nov. 2 Petraeomastus limenghuai sp. nov. 3 Petraeomastus limenghuai sp. nov. 4 Petraeomastus gredleri 1 Petraeomastus gredleri 2 Petraeomastus heudeanus 1 Petraeomastus heudeanus 2 Pupinidius porrectus 1 95/0.99 92/1 Pupinidius porrectus 2 Holcauchen sulcatus *% Achatinella sowerbyana Serina “Pupinidius ” Pupinidius Subzebrinus Clausiliopsis Turanena Pupopsis Mirus Dolichena Petraeomastus “Pupinidius ” Holcauchen Pupilla muscorum Camaena detianensis 0.1 outgroup Figure 1. Maximum likelihood tree and Bayesian inference tree inferred from CO/ and/6S gene sequences. Bootstrap supports/poste- rior probabilities are shown on the left/right of nodes on the tree if they are greater than 50%. Stars show the type species of the genera. thick, solid, opaque, sub-glossy, not speckled, not spiral- ly grooved; 8.0—8.5 whorls. Whorls rather flattened, not shouldered. Protoconch smooth, polished. Post-nuclear teleoconch ribbed. Growth lines indistinct. Suture rath- er deep, with an indistinct narrow band beneath it. Body whorl gradually ascending towards aperture, rounded at periphery. Aperture flat, truncate-ovate, oblique, without tooth, with shallow slightly out angular tubercle, com- pletely adnate to body whorl. Peristome connected, with a Shallow channel at upper insertion; white, thickened, expanded, not reflexed. Parietal callus distinct. Colu- mellar margin reflexed. Umbilicus narrowly open. Shell multicoloured, post-nuclear teleoconch with light brown backgroud and white ribs; apex region light brown. Genitalia. Vas deferens relative short, slightly swol- len distally; entering epiphallus apically with distinct de- marcation. Epiphallus long; cylindrical; rather straight; externally smooth. Epiphallic caecum present; blunt apically; located near vas deferens entrance. Flagellum long; tubular; proximally normal; with tip pointed. Penis zse.pensoft.net with terminal entrance of epiphallus; clavate; uniformly thickness. Penial caecum absent. Penial appendix long; branched off from penis at some distance from atri- um; divided into sections including A-1+A-2, A-3 and A-4+A-5. A-1 and A-2 fused. A-2 and A-3 not fused. Boundary between A-4 and A-5 indistinct. A-5 long; convoluted. Appendicular retractor and penial retractor long; biramous; attaching to penis middle part and to A-2 of penial appendix; with penial retractor arms arising from diaphragm closed to each other. Additional retrac- tor other than penial or appendicular absent. Muscular band connecting vagina and epiphallus absent. Atrium short; without retractor. Free oviduct longer than vagina. Vagina short; not swollen; straight; unpigmented. Bursa copulatrix duct short; proximally straight. Bursa copula- trix ovoid, with stalk; without apical ligament; normal in size; with short neck; well defined. Diverticle normally present; longer than bursa copulatrix; unexpanded. Bur- sa copulatrix and diverticle distinguishable; forked more distally from their base. Zoosyst. Evol. 100 (4) 2024, 1201-1209 1205 Figure 2. Petraeomastus limenghuai sp. nov. and three congeners with typical shell morphology. A. Holotype of Petraeomastus limenghuai sp. nov.; B. P. heudeanus, C. P. neumayri;, D. P. xerampelinus. Measurements. Holotype: shell height 20.6 mm, width 6.7 mm; aperture height 6.4 mm, width 4.7 mm. Paratypes: shell height 19.8—21.2 mm, width 6.0—7.0 mm; aperture height 6.0-6.6 mm, width 4.2-4.9 mm. Etymology. The species is named after Meng-Hua L1, who first discovered the new species and assisted in field surveys. Vernacular name. 22 3 Bae. Distribution and ecology. Known from the type lo- cality only (Figs 4, 5). Living on branches of bushes alongside P. heudeanus (Fig. 5). Although the two species are sympatric, it has been observed that Petraeomastus limenghuai sp. nov. is more common on the shady slopes, while P. heudeanus is more common on the sunny slopes. The distribution of Petraeomastus limenghuai sp. nov. 1s limited to the middle part of the valley within a few hun- dred meters and does not extend to the alpine meadows in the upper part. Only two empty shells were discovered at the lower part of the valley, which may have fallen from their original position. In contrast, P. heudeanus is widely distributed in the middle and lower parts of the valley, with numerous individuals observed in close proximity to the river channel. Discussion Only four enid species in China have a ribbed shell: Clausiliopsis clathratus (Mollendorff, 1901), Clausiliop- sis senckenbergianus Yen, 1939, Holcauchen multicosta- tus Chen, Xie, Wang & Wu, 2024, and Serina xirong Chen, Dai, Wu & Ouyang, 2024 (Mollendorff 1901; Yen 1939; Wu 2018; Chen et al. 2024a, 2024b). Petrae- omastus limenghuai sp. nov. can be distinguished from C. clathratus and C. senckenbergianus by absence of a tooth (vs. the presence of a parietal tooth). It resembles H. multicostatus and S. xirong, which also lack a tooth, but differs from them by having stronger ribs and a larger zse.pensoft.net 1206 Chen, Z.-G. et al.: A new species of Petraeomastus Figure 3. Genitalia of Petraeomastus limenghuai sp. nov. from both sides. Arrows show the forks. Shell (height 19.8—21.2 mm vs. 8.3—10.5 mm in H. multi- costatus and 9.7—11.0 mm in S. xirong). It further differs from H. multicostatus by having a more pointed shell and from S. xirong by having sparser ribs. Within the genus, the new species differs from congeners by the ribbed shell (vs. smooth in all congeners), the long flagellum (vs. short in P. breviculus, P. heudeanus, and P. platychilus), zse.pensoft.net and the unexpanded diverticle (vs. diverticle absent in P. breviculus, expanded in P. heudeanus, P. moellendorffi, P. mucronatus, P. platychilus, and P. semifartus). The shell morphology of Petraeomastus limenghuai sp. nov. is so unique that it is difficult to place it in any genus based on shell morphology alone. It also lacks diagnos- tic characteristics in its reproductive anatomy. Wu (2018) 1207 Zoosyst. Evol. 100 (4) 2024, 1201-1209 NovE Noc€ = Oo 2) Cc a) = O { @ a int. Maoxian; ; orange poin ; green point. Danba; Diebu. r. Rumei: Figure 4. Six dry-hot river valleys and the sample localities in them. Sta yellow point. Jiuzhaigou; purple point. Wudu; red point. Wenxian t e ; gray poin The Lancangjiang River Valley at Rumei; C, D. Petraeomastus li- B. . Habitat of Petraeomastus limenghuai sp. nov. A, Figure 5 menghuai sp. nov. in life. zse.pensoft.net 1208 proposed that the penial pilaster is a relatively stable char- acter in different genera, but we failed to dissect it because it was too thin (< 0.2 mm). However, the molecular phy- logeny strongly supported placement in Petraeomastus (bootstrap supports = 99, posterior probabilities = 1). All known species of Petraeomastus have a broad, cylindrical to conical, and smooth shell (Fig. 2B—D), which is signifi- cantly different from that of Petraeomastus limenghuai sp. nov. The shell morphology of land snails is frequently influenced by environmental selection, and the characters play a pivotal role in regulating the water and heat budget, thereby preventing desiccation (Cowie and Jones 1985; Chiba 2004; Pfenninger et al. 2005; Giokas et al. 2014). Considering that all Chinese Enidae with ribbed shells are distributed in the dry-hot river valleys (Mollendorff 1901; Yen 1939; Wu 2018; Chen et al. 2024a, 2024b), the spe- cial character that evolved independently in four genera may have been developed to adapt to the extremely dry and hot environment. The ribs on the shell could increase its surface area and may promote heat dissipation. Giokas et al. (2014) found that the ribbed shells in A/binaria Vest, 1867, retain more water on their shell surface, and the smooth shells exhibit lower water permeability. A similar phenomenon may also occur in Chinese Enidae, although further statistical study is required to confirm it. Current- ly, the proportion of known Chinese enid species with a ribbed shell is very low. Further comprehensive surveys of several dry-hot river valleys in southwest China might reveal additional species of Enidae with ribbed shells. Although 10 out of 12 genera of Enidae in China were included in this study, only 19 out of 185 species and sub- species were included. More comprehensive sampling is needed in future research. Currently, the taxonomy of enid genera in China is primarily based on shell morphol- ogy (Wu 2018). However, the shell morphology of land snails is frequently influenced by environmental factors (Cowie and Jones 1985; Chiba 2004; Pfenninger et al. 2005; Giokas et al. 2014) and is not stable. Some genital diagnostic characters of Chinese Enidae have been sum- marized (Wu 2018), but there is overlap between different genera in several characteristics. Currently, the diagnostic characters of Chinese Enidae are insufficiently defined at the genus level, as there is considerable overlap in char- acters among different genera. This presents a significant challenge in reliably distinguishing some genera from each other. The three clades of Pupinidius, which render the genus nonmonophyletic in the molecular phyloge- nies, exhibit a high similarity in shell morphology. Upon examination of a substantial number of specimens of the three clades, it is challenging to identify any reliable di- agnostic characters that distinguish them, both in terms of shell and genitalia. As a rock-dwelling group, the similar morphology between the three clades of Pupinidius may be attributed to convergent evolution due to similar envi- ronments. The inconsistency between the morphological characters and the molecular phylogenies also occurred in the new species described in this study and is possible to be prevalent in Chinese Enidae. The currently accepted zse.pensoft.net Chen, Z.-G. et al.: A new species of Petraeomastus classification of Chinese enids, which relies largely on shell morphology, may be problematic and is deemed to be in need of systematic revision. Acknowledgements We thank Menghua Li (Sichuan Agricultural University), Jinsheng Mou (China Agricultural University, Sichuan Agricultural University), Kaichen Ouyang (Kunming), and Shiyang Feng (Sichuan Agricultural University) for assistance in collecting specimens; Frank Kohler, Ruud Bank, and Aydin Orstan for their valuable comments on the manuscript. This study was supported by the Nation- al Natural Science Foundation of China under Grant No. 32360132, No. 31772412, the research project of the Zhe- jiang Natural History Museum under Grant No. 2024001, and the Biodiversity Monitoring Project of X1ixi1 National Wetland Park of Hangzhou. References Ai HM, Lin JH, Wang P, Zhou WC, Hwang CC (2016) Descriptions of two new species of the genus Camaena from guangxi, China (Gastropoda, Stylommatophora, Camaenidae). Zookeys 634(2): 29-45. https://doi.org/10.3897/zookeys.634. 10236 Ancey CMF (1883) Sur les mollusques des parties centrales de I’ Asie (Chine et Thibet). 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