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Research Article
A taxonomic revision of the freshwater crab genus Parvuspotamon Dai & Bo, 1994 (Decapoda, Brachyura, Potamidae), with descriptions of a new genus and two new species
expand article infoBoyang Shi‡, Da Pan‡, Hongying Sun‡
‡ Nanjing Normal University, Nanjing, China

Corresponding author: Da Pan ( dapan@njnu.edu.cn )

Corresponding author: Hongying Sun ( sunhongying@njnu.edu.cn )

Academic editor: Sameer Pati
© 2023 Boyang Shi, Da Pan, Hongying Sun.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation: Shi B, Pan D, Sun H (2023) A taxonomic revision of the freshwater crab genus Parvuspotamon Dai & Bo, 1994 (Decapoda, Brachyura, Potamidae), with descriptions of a new genus and two new species. ZooKeys 1183: 13-38. https://doi.org/10.3897/zookeys.1183.109948
ZooBank: urn:lsid:zoobank.org:pub:DA6935B9-D9E1-4B0B-8686-7B661CB9140E
Open Access

Abstract

The taxonomy of the potamid crab genus Parvuspotamon Dai & Bo, 1994, with two species native to Yunnan province of southwest China, is revised based on morphological and molecular data. In order to stabilise the taxonomy of these species (and the genus), two separate genera are hereby designated: Parvuspotamon and Songpotamon gen. nov. While Parvuspotamon is restricted to P. yuxiense Dai & Bo, 1994, as a monotypic genus, P. dixuense Naruse, Chia & Zhou, 2018, is transferred to a new genus, Songpotamon gen. nov. In addition, two new species of Songpotamon gen. nov. are described herein: S. funingense sp. nov. and S. malipoense sp. nov. Songpotamon gen. nov. morphologically most resembles Parvuspotamon and Chinapotamon Dai & Naiyanetr, 1994, but can be distinguished by the combination of characters in the carapace, third maxilliped, thoracic sternites, and male first gonopod. The genetic data derived from the mitochondrial 16S rDNA also supports the monophyly of these new taxa.

Key words

China, Crustacea, new combination, Potamiscinae, taxonomy, Yunnan

Introduction

The Yunnan Province of southwest China is noted for harbouring an exceptional number of freshwater species with a high level of endemism. This is widely recognised to be a direct consequence of the geological history of this mountainous region, e.g., orogenic processes and/or past climatic changes (Myers et al. 2000; Li et al. 2015; Antonelli et al. 2018; Rahbek et al. 2019; Pan et al. 2022). This diversity in landscape should have offered sufficient stability to the eco-environment, which not only supports the persistence of endemic species but also propels evolution and speciation (He and Jiang 2014; Atlas and Fu 2019; Ye et al. 2019; Wu et al. 2022).

Yunnan is a centre of diversification for Chinese freshwater crabs (Dai 1999; Cumberlidge et al. 2011). Although extensive research has been conducted on freshwater crabs in this region, the discovery of new genera and species still continues, and many new taxa have recently been revealed through morphological and molecular studies (Chu et al. 2017, 2018a, b; Naruse et al. 2018; Huang et al. 2020a, b; Wang et al. 2020; Zhang et al. 2020; Pan et al. 2021a, b, 2023; Tan et al. 2021; Shi et al. 2022). This is partly attributed to ongoing efforts focused on previously under-sampled areas.

The genus Parvuspotamon Dai & Bo, 1994, was erected for its type species Parvuspotamon yuxiense Dai & Bo, 1994, which is currently only known from Yuxi City, Yunnan Province. Naruse et al. (2018) recently described Parvuspotamon dixuense Naruse, Chia, & Zhou, 2018, from Yunnan, citing its morphological similarities with Parvuspotamon. Recent surveys in southwest China (Fig. 1) resulted in the collection of several freshwater crab specimens, which are similar to P. dixuense. Interestingly, these specimens are different from the type species of Parvuspotamon, i.e., P. yuxiense. After morphological comparisons and molecular phylogenetic inferences, we reveal that Parvuspotamon is polyphyletic and consists of two distinct clades. Parvuspotamon is therefore hereby revised, and a new genus, Songpotamon gen. nov., is established to accommodate P. dixuense and two new species, Songpotamon funingense sp. nov. and Songpotamon malipoense sp. nov.

Figure 1. 

Map of southeast Yunnan showing the distribution of three species of Songpotamon gen. nov.

Materials and methods

Crab collection

All individuals were collected from Yunnan Province. Specimens were preserved in 95% ethanol and were deposited at the Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China (NNU) and the Institute of Zoology, the Chinese Academy of Sciences, Beijing, China (CB). The terminology is after Ng (1988), with changes as recommended by Dai (1999) and Davie et al. (2015). The abbreviations used are as follows: asl., above sea level; G1, male first gonopod; G2, male second gonopod.

Phylogenetic analyses

DNA was extracted from gill or muscle tissues using the Trelief Animal Genomic DNA kit (Tsingke, Beijing, P.R. China) following the manufacturer’s protocol. A region of 490 base pairs (bp) of the 16S r DNA (16S) was amplified by polymerase chain reaction (PCR) using the primers 1471 and 1472 (Crandall and Fitzpatrick 1996). The PCR conditions included: initial denaturation at 95 °C for 3 min; 35 cycles of 30 s at 95 °C, 40 s at 50 °C, and 1 min at 72 °C; and a 7-min incubation at 72 °C. The following accession number were obtained from the GenBank: Songpotamon funingense gen. et sp. nov., OR469050, OR469051, OR469054, OR469055, OR469057, and OR469058; Songpotamon malipoense gen. et sp. nov., OR469052 and OR469053; Songpotamon dixuense (Naruse, Chia & Zhou, 2018) comb. nov., OR469056 and OR544490; and Parvuspotamon yuxiense, OR469059 (also see type material sections).

All sequences were aligned using MAFFT v.7.215 (Katoh and Standley 2013), with the iterative refinement method G-INS-i (accurate alignment). The 16S dataset was compiled from both GenBank (n = 18) and newly generated data (n = 11). The Maximum-likelihood (ML) phylogenetic inference was performed using IQ-TREE v. 1.6.10 (Nguyen et al. 2015). The best substitution model was selected using MODELFINDER (Kalyaanamoorthy et al. 2017) as implemented in IQ-TREE v. 2. The Bayesian Inference (BI) analysis was conducted in MRBAYES v. 3.2.7a (Ronquist et al. 2012). Four chains were run simultaneously (three heated, one cold) for 10,000,000 generations, with tree space sampled every 1,000 generations. After a graphical analysis of the evolution of the likelihood scores, the first 250,000 generations were discarded as burn-in. The remaining trees were used to calculate the consensus tree. Acceptable convergence to the stationary distribution was checked by inspecting the posterior samples using the diagnostic software TRACER v. 1.7 (Rambaut et al. 2018). Effective sample sizes were > 200 for all parameters. The pairwise genetic distance among each species were calculated using MEGA X under the pairwise Kimura two-parameter (K2P) model (Kimura 1980; Kumar et al. 2018).

Taxonomic account

Family Potamidae Ortmann, 1896

Subfamily Potamiscinae Bott, 1970 (sensu Yeo and Ng 2004)

Parvuspotamon Dai & Bo, 1994

Figs 2, 3, 4

Type species

Parvuspotamon yuxiense Dai & Bo, 1994, by original designation.

Diagnosis

Medium sized (adult carapace width 16–26 mm, n = 15). Carapace broader than long, ovate; dorsal surface convex, smooth, regions not clear; branchial regions swollen, smooth (Figs 2A, 4A). Epigastric cristae weakly developed, oblique, separated from each other by deep inverted Y-shaped groove; postorbital cristae low, indistinct, confluent with epigastric cristae (Figs 2A, 4A). External orbital angle bluntly triangular, outer margin and anterolateral margin of carapace confluent (Figs 2A, 4A). Anterolateral margin of carapace entire convex, smooth; posterolateral margins of carapace gently converging, smooth (Figs 2A, 4A). Epibranchial tooth indistinct (Figs 2A, 4A). Sub-orbital, sub-hepatic and pterygostomial regions smooth (Figs 2B, C, 4B, C). Antennular fossae slit-like in anterior view; median lobe of epistome posterior margin narrowly triangular (Figs 2B, 4B). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 3G). Thoracic sternites 3/4 in male completely fused (Figs 2C, 3C, E, 4C). Vulvae transversely ovate, widely located from each other, touching suture of sternites 5/6 (Fig. 3F). Male pleon broadly triangular (Figs 2C, 3C, 4C). G1 slender, reaching pleonal locking tubercle in situ (Figs 3E, H, I, 4D, E); subterminal segment stout, slightly sinuous (Figs 3H, I, 4D, E); terminal segment slender, relatively long, subconical, strongly sinuous, bent inwards, inner margin strongly concave, ~ 0.6× length of subterminal segment, without groove for G2 on ventral side, tip rounded, dorsal flap absent (Figs 3H, I, 4D–G). G2 longer than G1; terminal segment relatively long; subterminal segment ~ 1.5× length of terminal segment (Fig. 3J).

Figure 2. 

Parvuspotamon yuxiense Dai & Bo, 1994, ♂, 26.18 × 19.73 mm (NNU-3151-01) A overall dorsal view B overall frontal view C overall ventral view. Scale bars: 10 mm.

Figure 3. 

Parvuspotamon yuxiense Dai & Bo, 1994, ♂, 26.18 × 19.73 mm (NNU-3151-01) (A–C, E, G–J); ♀, 22.82 × 16.98 mm (NNU-3151-05) (D, F) A right chela B left chela C anterior thoracic sternum and pleon D pleon E thoracic sternum with right G1 in situ F thoracic sternum showing vulvae G left third maxilliped H dorsal view of left G1 I ventral view of left G1 J dorsal view of left G2. Scale bars: 10 mm (A–F); 1 mm (G–J).

Figure 4. 

Parvuspotamon yuxiense Dai & Bo, 1994, holotype ♂, 15.7 × 12.9 mm (CB05138 YN 9091116A) A overall dorsal view B overall frontal view C overall ventral view D dorsal view of left G1 E ventral view of left G1 F dorsal view of left G1 distal portion G ventral view of left G1 distal portion. Scale bars: 10 mm (A–C); 1 mm (D–G).

Remarks

Parvuspotamon was previously known by two species, P. yuxiense (type species) and P. dixuense. The latter species was recently described by Naruse et al. (2018) based on the characters in the carapace and G1 terminal segment. Based on morphological and molecular data, P. dixuense, however, is transferred to Songpotamon gen. nov. since it possesses the generic characters of the new genus (see Remarks for the new genus). The present revision thus restricts Parvuspotamon only to the type species, i.e., P. yuxiense.

The morphological similarities between Parvuspotamon and Songpotamon gen. nov. notwithstanding, Parvuspotamon can easily be distinguished from Songpotamon gen. nov. by the characters in the carapace, vulvae and G1 (see Remarks for Songpotamon gen. nov.). Parvuspotamon is immediately distinguished from most of the remaining Chinese potamid genera by the combination of its medium body size (adult carapace width 16–26 mm), the strongly sinuous G1 terminal segment, and the absence of a flagellum on the exopod of the third maxilliped (Dai and Bo 1994; Dai 1999).

Geographic distribution

Parvuspotamon is known only from Yunnan Province of southwest China.

Parvuspotamon yuxiense Dai & Bo, 1994

Figs 2, 3, 4

Type material

Holotype. China • ♂, 15.7 × 12.9 mm; Yunnan Province, Yuxi City, Xinping County, Gasa Township; Aug. 1990; CB05138 YN 9091116A.

Additional material

China • 4 ♂, 26.18 × 19.73 mm (NNU-3151-01), 23.26 × 17.19 mm (NNU-3151-02), 22.68 × 17.02 mm (NNU-3151-03), 20.79 × 15.52 mm (NNU-3151-04), 3 ♀, 22.82 × 16.98 (NNU-3151-05), 21.13 × 16.47 (NNU-3151-06), 22.59 × 17.35 (NNU-3151-07); Yunnan Province, Yuxi City, Xinping County, Heshalak Village; 23.96°N, 101.45°E; altitude 955 m asl; 11 Apr. 2019; Boyang Shi, Xiyang Hao, Zewei Zhang, and Hongying Sun, leg. • 5 ♂, 24.94 × 18.94 mm (NNU-1513-01), 21.16 × 16.86 mm (NNU-1513-02), 22.02 × 16.06 mm (NNU-1513-03), 18.72 × 13.42 mm (NNU-1513-04), 16.58 × 11.98 mm (NNU-1513-05), 2 ♀, 22.54 × 16.63 mm (NNU-1513-06), 17.12 × 12.77 mm (NNU-1513-07); Yunnan Province, Yuxi City, Gasha Town; 24.02°N, 101.58°E; altitude 795 m asl; 15 Oct. 2015; Kelin Chu, Qiang Zhao, Pengfei Wang, and Hongying Sun leg.

Description

Medium sized (adult carapace width 16–26 mm, n = 15). Carapace broader than long, ovate; dorsal surface convex both transversely and longitudinally, smooth, regions not clear; branchial regions swollen, smooth (Figs 2A, 4A). Postorbital and epigastric cristae confluent (Figs 2A, 4A); epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove (Figs 2A, 4A); postorbital cristae low, indistinct (Figs 2A, 4A). External orbital angle bluntly triangular, outer margin and anterolateral margin of carapace confluent (Figs 2A, 4A). Anterolateral margin of carapace entire convex, smooth; posterolateral margin gently concave, smooth, converging towards posterior carapace margin (Figs 2A, 4A). Epibranchial tooth indistinct (Figs 2A, 4A). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital, sub-hepatic, and pterygostomial regions smooth (Figs 2B, C, 4B, C). Antennular fossae slit-like in anterior view; median lobe of epistome posterior margin narrowly triangular (Figs 2B, 4B). Third maxilliped with rhombus ischium; exopod reaching beyond anterolateral corner of ischium, without flagellum (Fig. 3G).

Chelipeds unequal (Figs 2A–C, 3A, B, 4A–C). Merus trigonal in cross section; margins weakly crenulated (Figs 2A, 4A). Carpus with sharp spine at inner-distal angle (Figs 2A, 4A). Major cheliped palm length ~ 1.3× height (Fig. 3B). Occlusal margin of fingers with several small teeth; distinct gape when closed (Fig. 3A, B).

Ambulatory legs not distinctly elongated, dactyli slender (Figs 2A, C, 4A, C); second pair longest, last pair shortest (Figs 2A, C, 4A, C). Outer surface of merus weakly rugose, dorsal margin weakly serrated, without subdistal tooth, length ~ 4.1× width (Figs 2A, 4A).

Male thoracic sternum smooth, weakly pitted; sternites 1/2 fused forming triangular structure; sternites 2/3 separated by deep but incomplete groove; sternites 3/4 completely fused; median longitudinal suture of sternites 7/8 deep (Figs 2C, 3C, E, 4C). Vulvae transversely ovate, widely located from each other, touching suture of sternites 5/6, posteromesial margin with low rim, opened obliquely upwards (Fig. 3F).

Male pleon broadly triangular; male telson relatively broad, lateral margins concave, width ~ 1.4× length; male pleonal somite 6 trapezoidal, broad, width ~ 2.3× length; somites 3–5 trapezoidal, gradually decreasing in width; somite 2 trapezoidal, reaching to bases of coxae of fourth ambulatory legs, thoracic sternite 8 not visible when pleon closed (Figs 2C, 3C, 4C). Female pleon ovate, covering most of thoracic sternum (Fig. 3D).

G1 slender, reaching pleonal locking tubercle in situ, with terminal and subterminal segments clearly demarcated (Figs 3E, H, I, 4D–G); subterminal segment stout, slightly sinuous (Figs 3H, I, 4D, E); terminal segment slender, relatively long, subconical, strongly sinuous, bent inwards, inner margin strongly concave, ~ 0.6× length of subterminal segment, without groove for G2 on ventral side, tip rounded, dorsal flap absent (Figs 3H, I, 4D–G). G2 longer than G1; terminal segment relatively long; subterminal segment ~ 1.5× length of terminal segment (Fig. 3J).

Colour in life

Carapace and chelipeds are generally yellowish brown in mature individuals.

Habitat

Parvuspotamon yuxiense can be found under rocks in hill streams at ~ 700–1000 m altitude.

Remarks

Parvuspotamon yuxiense is the sole species of the genus and closely related to the species of Songpotamon gen. nov., and two species of Tenuipotamon Dai, 1990 (Tenuipotamon yuxiense Chen, 1993, and Tenuipotamon xingpingense Chen, 1993) that are known from Xinping County, Yuxi City of Yunnan Province. Parvuspotamon yuxiense can nevertheless be differentiated from T. yuxiense and T. xingpingense by the following characters: anterolateral margins of the carapace entire and smooth (vs cristate); and G1 terminal segment relatively less strongly curved, lacking a dorsal flap (vs more strongly curved, with a distinct dorsal flap) [cf. Chen 1993: figs 3 (4–6), 4 (4–6)]. On the other hand, P. yuxiense can be differentiated from the species of Songpotamon gen. nov. by the characters in the carapace, vulvae and G1 (see Remarks for Songpotamon gen. nov.).

Geographic distribution

Parvuspotamon yuxiense is known only from the Yuxi City, Yunnan Province, southwest China.

Songpotamon gen. nov.

https://zoobank.org/8CCC83D0-C234-4C34-AB6B-A3580AF601CD
Figs 5, 6, 7, 8, 9, 10

Type species

Songpotamon funingense sp. nov., by present designation.

Species included

Songpotamon dixuense (Naruse, Chia & Zhou, 2018), comb. nov., Songpotamon funingense gen. et sp. nov., and Songpotamon malipoense gen. et sp. nov.

Diagnosis

Medium sized (adult carapace width 19–27 mm, n = 16). Carapace broader than long, ovate; dorsal surface convex, generally smooth, pitted, regions not clear; branchial regions swollen (Figs 5A, 7A). Postorbital and epigastric cristae not confluent, separated by shallow groove (Figs 5A, 7A). External orbital angle bluntly triangular, outer margin separated from anterolateral margin of carapace by shallow cleft (Figs 5A, 7A). Anterolateral margin of carapace convex (Figs 5A, 7A). Orbits large; supraorbital and infraorbital margins smooth (Figs 5B, 7B). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Figs 6C, 8C). Thoracic sternites 3/4 in male fused except for incomplete groove demarcating suture (Figs 5C, 6E, G, 7C, 8E, G). Vulvae transversely ovate, relatively closely located to each other, touching suture of sternites 5/6 (Figs 6H, 8H). Male pleon narrowly triangular (Figs 5C, 6E, 7C, 8E). G1 slender, almost reaching or reaching beyond pleonal locking tubercle in situ (Figs 6G, 8G, 9A, B, D, E, 10A–D); terminal segment slender, subconical, bent outwards, relatively short, ~ 0.4× length of subterminal segment, with distinct groove for G2 on ventral side, tip subtruncate, gently recurved upwards, dorsal flap absent (Figs 9A, B, D, E, 10A–D). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5× length of terminal segment (Fig. 9C, F).

Figure 5. 

Songpotamon funingense gen. et sp. nov., holotype ♂, 27.2 × 21.9 mm (NNU-167462-01) A overall dorsal view B frontal view of cephalothorax C overall ventral view. Scale bars: 10 mm.

Figure 6. 

Songpotamon funingense gen. et sp. nov., holotype ♂, 26.18 × 19.73 mm (NNU-3151-01) (A–E, G); paratype ♀, 22.6 × 18.0 mm (NNU-167462-05) (F, H) A right chela B left chela C left third maxilliped D right second ambulatory leg E anterior thoracic sternum and pleon F pleon G thoracic sternum with right G1 in situ H thoracic sternum showing vulvae. Scale bars: 10 mm.

Figure 7. 

Songpotamon malipoense gen. et sp. nov., holotype ♂, 21.7 × 16.8 mm (NNU-167444-01) A overall dorsal view B overall frontal view C overall ventral view. Scale bars: 10 mm.

Figure 8. 

Songpotamon malipoense gen. et sp. nov., holotype ♂, 21.7 × 16.8 mm (NNU-167444-01) (A–E, G); paratype ♀, 20.7 × 16.7 mm (NNU-167444-05) (F, H) A right chela B left chela C left third maxilliped D right second ambulatory leg E anterior thoracic sternum and pleon F pleon G thoracic sternum with right G1 in situ H thoracic sternum showing vulvae. Scale bars: 10 mm.

Figure 9. 

Songpotamon funingense gen. et sp. nov., holotype ♂, 27.2 × 21.9 mm (NNU-167462-01) (A–C). Songpotamon malipoense gen. et sp. nov., holotype ♂, 21.7 × 16.8 mm (NNU-167444-01) (D–F) A, D dorsal view of left G1 B, E ventral view of left G1 C, F dorsal view of left G2. Scale bars: 1 mm.

Etymology

The genus is named after the late Prof. Daxiang Song, a senior academician in the Chinese Academy of Sciences, in the honour of his immense contributions to Chinese invertebrate systematics; in arbitrary combination with the genus name Potamon Savigny, 1816. Gender of genus neuter.

Remarks

Songpotamon gen. nov. is established for S. dixuense comb. nov. and two new species, S. funingense sp. nov. and S. malipoense sp. nov. Songpotamon dixuense comb. nov. was previously in Parvuspotamon, but here transferred to Songpotamon gen. nov. because it possesses the key generic characters of the new genus, which includes, the medium body size (adult carapace width 19–27 mm), the third maxilliped exopod lacking a flagellum, the external orbital angle being bluntly triangular, the slender G1 shape, and the terminal segment being subconical and with a groove for G2 on the ventral side (cf. Naruse et al. 2018: figs 24–27).

Songpotamon gen. nov. can easily be distinguished from Parvuspotamon by the following characters: 1) carapace dorsal surface with scattered pits (Figs 5A, 7A; cf. Naruse et al. 2018: fig. 25A) (vs smooth; Figs 2A, 4A); 2) outer margin of the external orbital angle separated from the anterolateral margin of the carapace by the shallow cleft (Figs 5A, 7A; cf. Naruse et al. 2018: fig. 25A) (vs confluent with each other; Figs 2A, 4A); 3) vulvae relatively close located to each other (Figs 6H, 8H; cf. Naruse et al. 2018: fig. 27) (vs relatively widely located from each other; Fig. 3F); 4) G1 terminal segment relatively shorter, ~ 0.4× the length of the subterminal segment, with a truncated tip (Figs 9A, B, D, E, 10A–D; cf. Naruse et al. 2018: fig. 26A–D) (vs relatively longer, ~ 0.6× the length of the subterminal segment, with a rounded tip; Figs 3H, I, 4D–G); 5) G1 terminal segment bent outwards but with the tip gently recurved upwards, the inner margin being straight to gently curved (Figs 9A, B, D, E, 10A–D; cf. Naruse et al. 2018: fig. 26 A–D) (vs bent inwards, with the inner margin being strongly concave; Figs 3H, I, 4D–G); and 6) groove for G2 on the G1 terminal segment clearly visible in the ventral view (Figs 9 B, E, 10B, D; cf. Naruse et al. 2018: fig. 26A, B) (vs not visible; Figs 3I, 4E, G).

Furthermore, Songpotamon gen. nov. is most likely to be confused with Chinapotamon Dai & Naiyanetr, 1994, as both the genera have a very similar carapace physiognomy, and their G1 terminal segment is subconical, with the groove for G2 visible in the ventral view. The new genus, Songpotamon gen. nov., is nevertheless distinguished from Chinapotamon by the following characters: 1) carapace relatively high (Figs 5B, 7B) (vs relatively low); 2) ambulatory legs relatively stout (Figs 5A, C, 6D, 7A, C, 8D) (vs relatively slender); 3) anterolateral margin of the carapace being less convex (Figs 5A, 7A) (vs strongly convex); 4) third maxilliped exopod without flagellum (Figs 6C, 8C) (vs with well-developed flagellum); 5) thoracic sternites 3/4 with incomplete but distinct groove demarcating suture (Figs 5C, 6E, G, 7C, 8E, G) (vs groove demarcating suture absent); and 6) G1 terminal segment gently curved outwards (Figs 9A, B, D, E, 10A–D) (vs strongly bent outwards) (cf. Dai 1999: figs 42–47; Ng 2017: figs 2–4, 6–8; Zou et al. 2018: figs 2–6).

Geographic distribution

Songpotamon gen. nov. is known from Wenshan Prefecture, eastern Yunnan Province, southwest China.

Songpotamon funingense gen. et, sp. nov.

https://zoobank.org/8C1EEA1D-F6D9-4256-B0D4-1599AA753C99
Figs 5, 6, 9A–C, 10A, B

Type material

Holotype. China • ♂, 27.2 × 21.9 mm; Yunnan Province, Wenshan Prefecture, Funing County, Tianwan Township; 23.20°N, 104.87°E; altitude 880 m asl.; 22 Oct. 2020; Boyang Shi, Ruxiao Wang, and Hongying Sun leg.; GenBank: OR469050; NNU-167462-01.

Paratype. China • ♂, 25.2 × 20.9 mm; same collection data as for holotype; GenBank: OR469051; NNU-167462-02 • ♂, 26.6 × 21.0 mm; same collection data as for holotype; GenBank: OR469057; NNU-167462-03 • ♂, 23.5 × 19.1 mm; same collection data as for holotype; GenBank: OR469058; NNU-167462-04 • ♀, 22.6 × 18.0 mm; same collection data as for holotype; NNU-167462-05 • ♀, 24.6 × 19.7 mm; same collection data as for holotype; NNU-167462-06 • ♂, 22.2 × 17.8 mm; Yunnan Province, Wenshan Prefecture, Funing County, Longbo Township; 23.31°N, 105.46°E; altitude 1611 m asl.; 24 Oct. 2020; Boyang Shi, Ruxiao Wang, and Hongying Sun leg.; GenBank: OR469054; NNU-167533-01 • ♂, 21.5 × 17.7 mm; same collection data as for NNU-167533-01; GenBank: OR469055; NNU-167533-02 • ♀, 20.8 × 16.4 mm; same collection data as for NNU-167533-01; NNU-167533-03.

Diagnosis

Medium sized (adult carapace width 21–27 mm, n = 9). Carapace broader than long, ovate; dorsal surface convex, smooth, pitted, regions not clear; branchial regions swollen (Fig. 5A). Postorbital and epigastric cristae low, not confluent, separated by weak shallow groove (Fig. 5A); epigastric cristae weakly developed, straight, separated by shallow inverted Y-shaped groove; postorbital cristae low, rugose (Fig. 5A). External orbital angle bluntly triangular, outer margin convex, separated from anterolateral margin of carapace by shallow cleft (Fig. 5A). Anterolateral margin of carapace convex, generally smooth, weakly cristate; posterolateral margins gently converging, smooth (Fig. 5A). Orbits large; supraorbital and infraorbital margins smooth (Fig. 5B); sub-orbital, sub-hepatic and pterygostomial regions smooth or weakly rugose (Fig. 5B, C). Antennular fossae rectangular in anterior view; median lobe of epistome posterior margin low, rounded (Fig. 5B). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 6C). Thoracic sternites 3/4 in male fused except for relatively deep, incomplete groove demarcating suture (Figs 5C, 6E, G). Vulvae transversely ovate, closely located to each other, touching suture of sternites 5/6, opened obliquely ~ 45° upwards (Fig. 6H). Male pleon narrowly triangular; somite 6 relatively narrow, width ~ 2.4× as length (Fig. 5C). G1 slender, almost reaching pleonal locking tubercle in situ (Figs 6G, 9A, B, 10A, B); subterminal segment stout, sinuous, inner margin concave; terminal segment subconical, bent at ~ 45° outwards, relatively short, ~ 0.4× length of subterminal segment, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9A, B, 10A, B). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5× length of terminal segment (Fig. 9C).

Description

Medium sized (adult carapace width 21–27 mm, n = 9). Carapace broader than long, ovate; dorsal surface convex transversely, longitudinally, smooth, pitted, regions not clear; branchial regions swollen, smooth (Fig. 5A). Postorbital and epigastric cristae inconspicuous, not confluent, separated by weakly shallow groove (Fig. 5A); epigastric cristae weakly developed, straight, separated by shallow Y-shaped groove; postorbital cristae low, rugose, reaching epibranchial tooth (Fig. 5A). Cervical groove indistinct (Fig. 5A). External orbital angle bluntly triangular, outer margin straight, with shallow cleft demarcating it from epibranchial tooth; epibranchial tooth weakly developed (Fig. 5A). Anterolateral margin convex, smooth, weakly cristate; posterolateral margin gently concave, smooth, converging towards posterior carapace margin (Fig. 5A). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital, sub-hepatic, and pterygostomial regions relatively smooth or weakly rugose (Fig. 5B, C). Antennular fossae rectangular in anterior view; median lobe of epistome posterior margin low, rounded (Fig. 5B). Third maxilliped with rhombus ischium; exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 6C).

Chelipeds unequal (Figs 5A, C, 6A, B). Merus trigonal in cross section; margins crenulated (Fig. 5A, C). Carpus with sharp spine at inner-distal angle (Fig. 5A, C). Major cheliped palm length ~ 1.4× as height (Fig. 6B). Occlusal margin of fingers with sharp teeth; distinct gape when closed (Fig. 6B).

Ambulatory legs not distinctly elongated, dactyli slender (Figs 5A, C, 6D); second pair longest, last pair shortest (Fig. 5A, C). Outer surface of merus slightly rugose, dorsal margin weakly serrated, without subdistal tooth, length ~ 3.7× as width (Fig. 6D).

Male thoracic sternum generally smooth, weakly pitted; sternites 1/2 fused to form a triangular structure (Figs 5C, 6E, G); sternites 2/3 demarcated by horizontal groove; sternites 3/4 fused except for relatively deep, incomplete groove demarcating suture (Figs 5C, 6E, G); median longitudinal suture of sternites 7/8 deep (Fig. 6E, G). Vulvae transversely ovate, closely located to each other, touching suture of sternites 5/6, opened obliquely ~ 45° upwards, posteromesial margin with low raised rim (Fig. 6H).

Male pleon narrowly triangular; telson relatively broad, lateral margins slightly convex, width ~ 1.2× as length (Figs 5C, 6E); somite 6 broadly rectangular, width ~ 2.4× as length; suture between somites 6/7 sinuous; somites 3–5 trapezoidal, gradually decreasing in width; somite 2 trapezoidal, reaching to bases of coxae of fourth ambulatory legs; thoracic sternite 8 not visible when pleon closed (Figs 5C, 6E). Female pleon ovate, covering most of thoracic sternum (Fig. 6F).

G1 slender, almost reaching pleonal locking tubercle in situ, with terminal and subterminal segments clearly demarcated (Figs 6G, 9A, B, 10A, B); subterminal segment stout, sinuous, distal part prominently narrow, inner margin concave (Figs 9A, B, 10A, B); terminal segment slender, subconical, bent at ~ 45° outwards, relatively short, ~ 0.4× length of subterminal segment, outer margin slightly convex, inner margin straight, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9A, B, 10A, B). G2 longer than G1, terminal segment relatively short; subterminal segment ~ 5× length of terminal segment (Fig. 9C).

Etymology

The species is named after Funing County, the type locality of the new species in the Yunnan Province of China.

Colour in life

Carapace and chelipeds are generally bright orange to red with purplish brown ambulatory legs in mature individuals. Generally purplish brown all over with bright orange tips of the chelipeds in smaller individuals.

Habitat

This new semi-terrestrial species digs and inhabits mud burrows close to small hill streams and seeps.

Remarks

The new species most closely resembles S. malipoense gen. et sp. nov., in general carapace morphology, especially in possessing the relatively narrower male pleonal somite 6, the recurved tip of the G1 terminal segment, and the distinct and entire groove for the G2 on the ventral side of the G1 terminal segment. Songpotamon funingense gen. et sp. nov., however, can be separated from S. malipoense gen. et sp. nov. by the following characters: 1) anterolateral margins of the carapace generally smooth (Fig. 5A) (vs with small granules; Fig. 7A); epigastric cristae straight in dorsal view and separated from each other by a shallow inverted Y-shaped groove (Fig. 5A) (vs oblique in dorsal view and separated from each other by a relatively deep inverted Y-shaped groove; Fig. 7A); male thoracic sternites 3/4 with relatively deep groove demarcating suture (Figs 5C, 6E, G) (vs relatively shallow; Figs 7C, 8E, G); vulvae opening obliquely ~ 45° upwards (Fig. 6H) (vs opening inwards; Fig. 9H); G1 subterminal segment relatively stouter, with the inner margin concave (Figs 9A, B, 10A, B) (vs relatively slenderer, with the inner margin almost straight; Figs 9D, E, 10C, D); and G1 terminal segment strongly bent at ~ 45° outwards (Figs 9A, B, 10A, B) (vs gently curved at ~ 30° outwards ; Figs 9D, E, 10C, D).

Figure 10. 

Songpotamon funingense gen. et sp. nov., holotype ♂, 27.2 × 21.9 mm (NNU-167462-01) (A, B). Songpotamon malipoense gen. et sp. nov., holotype ♂, 21.7 × 16.8 mm (NNU-167444-01) (C, D) A, C dorsal view of left G1 B, D ventral view of left G1. Scale bars: 1 mm.

The new species is also morphologically similar to S. dixuense comb. nov. in the weakly developed epibranchial tooth, the relatively smooth sub-orbital, sub-hepatic, and pterygostomial regions, and the sinuous subterminal segment of the G1. Songpotamon funingense gen. et sp. nov., however, can be distinguished from S. dixuense comb. nov. by the following characters: antennular fossae subrectangular (Fig. 5B) (vs slit-like); male pleonal somite 6 relatively narrower (Fig. 5C) (vs relatively broader); vulvae opening distinctly oblique ~ 45° upwards (Fig. 6H) (vs opening slightly oblique ~ 30° upwards); G1 subterminal segment relatively stouter (Figs 9A, B, 10A, B) (vs relatively slenderer); and G1 terminal segment relatively strongly bent at ~ 45° outwards (Figs 9A, B, 10A, B) (vs gently curved at ~ 30° outwards) (cf. Naruse et al. 2018: figs 24B, 26, 27).

Geographic distribution

Songpotamon funingense gen. et sp. nov. is known from Funing County, eastern Wenshan Prefecture, Yunnan Province, southwest China.

Songpotamon malipoense gen. et, sp. nov.

https://zoobank.org/6D3DB24F-9039-4DDB-A1C7-F0F46443826C
Figs 7, 8, 9D–F, 10C, D

Type material

Holotype. China • ♂, 21.7 × 16.8 mm; Yunnan Province, Wenshan Prefecture, Malipo County, Tiechang Township; 23.20°N, 104.83°E; altitude 864 m asl.; 24 Oct. 2020; Boyang Shi, Ruxiao Wang, and Hongying Sun leg.; GenBank: OR469052; NNU-167444-01.

Paratype. China • ♂, 22.1 × 17.8 mm; same collection data as for holotype; GenBank: OR469053; NNU-167444-02 • ♂, 20.3 × 16.2 mm; same collection data as for holotype; NNU-167444-03 • ♂, 19.6 × 15.7 mm; same collection data as for holotype; NNU-167444-04 • ♀, 20.7 × 16.7 mm; same collection data as for holotype; NNU-167444-05 • ♀, 20.5 × 15.4 mm; same collection data as for holotype; NNU-167444-06 • ♀, 18.6 × 14.3 mm; same collection data as for holotype; NNU-167444-07.

Diagnosis

Medium sized (adult carapace width 19–22 mm, n = 7). Carapace broader than long, ovate; dorsal surface convex, smooth, pitted, regions not clear; branchial regions swollen, smooth (Fig. 7A). Postorbital and epigastric cristae inconspicuous, not confluent, separated by shallow groove (Fig. 7A); epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove; postorbital cristae low, weakly rugose (Fig. 7A). External orbital angle bluntly triangular, outer margin convex, separated from anterolateral margin of carapace by shallow cleft (Fig. 7A). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae (Fig. 7A). Orbits large; sub-orbital regions smooth; sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C). Antennular fossae semi-circular; median lobe of epistome posterior margin broadly triangular (Fig. 7B). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C). Thoracic sternites 3/4 in male fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C, 8E, G). Vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5/6, opened inwards (Fig. 8H). Male pleon narrowly triangular; somite 6 relatively narrow, width ~ 2.5× as length (Fig. 8E). G1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4/5 in situ (Figs 8G, 9D, E, 10C, D); subterminal segment relatively slender, gently sinuous, inner margin almost straight; terminal segment short, slender, subconical, relatively less strongly bent at ~ 30° outwards, ~ 0.4× length of subterminal segment, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9D, E, 10C, D). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5× length of terminal segment (Fig. 9F).

Description

Medium sized (adult carapace width 19–22 mm, n = 7). Carapace broader than long, ovate; dorsal surface convex transversely, longitudinally, smooth, pitted, regions not clear; branchial region swollen, smooth (Fig. 7A). Postorbital and epigastric cristae inconspicuous, not confluent, separated by shallow groove; epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove; postorbital cristae low, weakly rugose, reaching epibranchial tooth (Fig. 7A). Cervical groove distinct, shallow (Fig. 7A). External orbital angle bluntly triangular, outer margin convex, with shallow cleft demarcating it from epibranchial tooth; epibranchial tooth weakly developed (Fig. 7A). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae, converging towards posterior carapace margin (Fig. 7A). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital regions smooth, sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C). Antennular fossae semi-circular in anterior view; median lobe of epistome posterior margin broadly triangular (Fig. 7B). Third maxilliped with subrectangular ischium; exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C).

Chelipeds unequal (Figs 7A, C, 8A, B). Merus trigonal in cross section; margins crenulated (Fig. 7A, C). Carpus with bluntly stout spine at inner-distal angle (Fig. 7A, C). Major cheliped palm length ~ 1.2× as height (Fig. 8A). Occlusal margin of fingers with rounded, blunt teeth; distinct gape when closed (Fig. 8A).

Ambulatory legs not elongated, slender dactyli (Figs 7A, C, 8D); second pair longest, last pair shortest (Fig. 7A, C). Outer surface of merus slightly rugose, dorsal margin weakly serrated, without subdistal tooth, length ~ 3.5× as width (Fig. 8D).

Male thoracic sternum generally smooth, weakly pitted; sternites 1/2 fused forming triangular structure (Figs 7C, 8E, G); sternites 2/3 demarcated by horizontal groove; sternites 3/4 fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C, 8E, G); median longitudinal suture of sternites 7/8 deep (Fig. 8E, G). Vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5/6, opened inwards, posteromesial margin with low raised rim (Fig. 8H).

Male pleon narrowly triangular; telson relatively broad, lateral margins slightly convex, width ~ 1.3× as length (Figs 7C, 8E); somite 6 broadly rectangular, width ~ 2.5× as length; suture between somites 6/7 sinuous; somites 3–5 trapezoidal, gradually decreasing in width; somite 2 trapezoidal, reaching to bases of coxae of fourth ambulatory legs; thoracic sternite 8 not visible when pleon closed (Figs 7C, 8E). Female pleon ovate, covering most of thoracic sternum (Fig. 8F).

G1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4/5 in situ, with terminal and subterminal segments clearly demarcated (Figs 8G, 9D, E, 10C, D); subterminal segment relatively slender, gently sinuous, distal part prominently narrow, inner margin almost straight (Figs 9D, E, 10C, D); terminal segment short, slender, subconical, relatively less strongly bent at ~ 30° outwards, ~ 0.4× length of subterminal segment, outer margin convex, inner margin convex, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9D, E, 10C, D). G2 longer than G1, terminal segment relatively short; subterminal segment ~ 5× length of terminal segment (Fig. 9F).

Etymology

The species is named after Malipo County, the type locality of the new species in the Yunnan Province of China.

Colour in life

The dorsal surface of the carapace is dark brown, with brighter chelae; the ventral surface is paler.

Habitat

Songpotamon malipoense gen. et sp. nov. is usually found hiding under rocks in small hill streams. Some large specimens have nevertheless been collected from deep mud burrows at the bank of hill streams, suggesting a semi-terrestrial lifestyle.

Remarks

The new species superficially resembles S. dixuense comb. nov. in overall carapace physiognomy, especially in possessing the granular anterolateral margin of the carapace and the relatively slender G1. Songpotamon malipoense gen. et sp. nov., however, can immediately be distinguished from S. dixuense comb. nov. by the following characters: 1) carapace dorsal surface glabrous, with dense pits (Fig. 7A) (vs with few short setae and scattered pits); 2) inverted Y-shaped groove between the epigastric cristae relatively deep (Fig. 7A) (vs relatively shallow); 3) chela generally smooth on the outer surface (Fig. 8A) (vs relatively rugose); 4) pterygostomial regions with prominent rounded granules (Fig. 7B) (vs relatively smooth); 5) antennular fossae rectangular in anterior view (Fig. 7B) (vs slit-like); 6) median tooth on the epistome posterior margin broadly triangular (Fig. 7B) (vs narrowly triangular); 7) male pleonal somite 6 relatively narrower (vs relatively broader); and 8) G1 with an almost straight inner margin of the subterminal segment (Fig. 9D, E, 10C, D) (vs with a gently concave inner margin) (cf. Naruse et al. 2018: figs 24A, B, 25B, 26A, C). Biogeographically, these two species are also isolated due to their occurrence in different drainages, with the new species in the Yuanjiang-Red River Basin and S. dixuense comb. nov. in the Pearl River Basin (Fig. 1). Songpotamon malipoense gen. et sp. nov. need not be confused with S. funingense gen. et sp. nov. (see Remarks for the latter new species).

Geographic distribution

Songpotamon malipoense gen. et sp. nov. is known from Malipo County, southern Wenshan Prefecture, Yunnan Province, southwest China.

Phylogenetic analysis and discussion

A total of 18 potamid species from 10 genera, including the new genus and two new species, and P. yuxiense, were used in the analysis. A 490 bp 16S rDNA segment, excluding the variable regions, was aligned. ML and BI analyses resulted in congruent tree topologies with some minor differences in the terminal lineages. The phylogenetic results inferred that two new species and S. dixuense comb. nov. formed a well-supported monophyletic lineage (Fig. 11). Parvuspotamon yuxiense is situated at a basal position and is far away from the new genus, Songpotamon gen. nov., in the phylogenetic tree. Songpotamon gen. nov. is phylogenetically more closely related to Diyutamon Huang, Shih & Ng, 2017, and Chinapotamon than to Parvuspotamon, occurring in southeast Yunnan. These genera, however, are not only morphologically distinct but also characterised by different geographic distributions and habitats, i.e., Diyutamon colonised subterranean karst streams (Huang et al. 2017), and Chinapotamon occurred in both subterranean karst streams and hill streams (Dai and Naiyanetr 1994; Ng 2017; Zou et al. 2018).

Figure 11. 

Maximum Likelihood phylogenetic tree based on 16S rDNA sequences. Support values at the nodes represent the > 50% posterior probabilities (PP) and bootstrap values (BV) for BI and ML (PP/BV), respectively. The new sequences are indicated in bold font. Asterisks indicate PP = 1.00 or BS = 100.

The phylogenetic trees suggested that two new species of Songpotamon gen. nov. cluster with their congener S. dixuense comb. nov. Songpotamon malipoense gen. et sp. nov. is close to S. dixuense comb. nov. (PP/BV = 0.96/89), whereas S. funingense gen. et sp. nov. is positioned outside (PP/BV = 1/100). The pairwise distance based on the Kimura 2 parameter model showed that most of the pairwise genetic distances between the 12 species beyond a threshold of 0.04 (Table 1). The genetic distances between Songpotamon gen. nov. and the other genera ranged from 0.042 to 0.178, and the minimum value within Songpotamon gen. nov. was 0.042. Considering the profound morphological differences and the genus/species level genetic divergence among these genera and species, we revealed that Songpotamon gen. nov. and the two new species of this new genus, indeed represent distinct taxa of Potamidae.

Table 1
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Matrix of pairwise nucleotide divergences based on the Kimura 2 parameter model using 16S rDNA sequences between the species of Songpotamon gen. nov., Parvuspotamon, Cantopotamon, Chinapotamon, Diyutamon, and Qianguimon.

1 2 3 4 5 6 7 8 9 10 11
1. Parvuspotamon yuxiense
2. Cantopotamon hengqinense 0.135
3. Cantopotamon shangchuanense 0.148 0.059
4. Chinapotamon longlinense 0.162 0.073 0.080
5. Chinapotamon depressum 0.159 0.073 0.088 0.006
6. Chinapotamon glabrum 0.165 0.064 0.083 0.026 0.028
7. Diyutamon cereum 0.148 0.062 0.074 0.053 0.055 0.046
8. Qianguimon elongatum 0.156 0.068 0.075 0.080 0.082 0.080 0.069
9. Qianguimon splendidum 0.154 0.080 0.085 0.090 0.092 0.085 0.067 0.041
10. Songpotamon dixuense comb. nov. 0.163 0.067 0.088 0.062 0.065 0.044 0.042 0.078 0.081
11. Songpotamon malipoense gen. et sp. nov. 0.160 0.068 0.090 0.066 0.068 0.052 0.044 0.084 0.084 0.042
12. Songpotamon funingense gen. et sp. nov. 0.178 0.083 0.097 0.084 0.087 0.068 0.074 0.098 0.104 0.054 0.060

Geographically, the three species of Songpotamon gen. nov. occur in two different drainages, with S. dixuense comb. nov. occurring in the Tuoniang River (tributaries of the Pearl River), and the two new species in the Panlong River and Nanli River, respectively (tributaries of Yuanjiang-Red River) (Fig. 1). Previous studies of stream-associated freshwater crabs have shown that drainage systems can drive species divergence and biogeographical patterns (Daniels et al. 2015; Fang et al. 2015; Shi et al. 2021). In the present study, we inferred the two hydrologic systems may contributed the genetic divergence between S. dixuense comb. nov. and the two new species of Songpotamon gen. nov. Meanwhile, the species divergence between two new species may be attributed to local adaptive evolution in different tributaries.

Acknowledgments

We are grateful to Ruxiao Wang (College of Life Sciences, Nanjing Normal University) for assistance with the collection of samples, and Hui Chen for taking the photographs. We thank Kangqin Zhang, Tianyu Gu, and Caixin Liu (Nanjing Normal University) for their help with DNA extractions. Thanks are also due to Dr. Jiexin Zou, Dr. Chunchao Zhu, and Dr. Xianmin Zhou (Nanchang University) for providing photographs of Parvuspotamon yuxiense. We thank the editor Dr. Sameer Kumar Pati and the reviewer Dr. Chao Huang for their invaluable comments and suggestions, which significantly helped to improve the manuscript.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This project was supported by the National Natural Science Foundation of China (No. 32200356 to PD, and No. 32170454 & 31772427 to SHY), and the Natural Science Foundation of the Jiangsu Higher Education Institutions (No. 22KJB180018 to PD).

Author contributions

B.Y. Shi, D. Pan, and H.Y. Sun conceived the study; B.Y. Shi and H.Y. Sun collected the samples; B.Y. Shi prepared them for DNA sequencing and carried out the analyses; B.Y. Shi, D. Pan, and H.Y. Sun wrote and approved the final manuscript.

Author ORCIDs

Boyang Shi https://orcid.org/0000-0003-3306-3764

Da Pan https://orcid.org/0000-0001-5445-6423

Hongying Sun https://orcid.org/0000-0003-2311-1814

Data availability

All of the data that support the findings of this study are available in the main text.

References

  • Antonelli A, Kissling WD, Flantua SGA, Bermúdez MA, Mulch A, Muellner-Riehl AN, Kreft H, Linder HP, Badgley C, Fjeldså J, Fritz SA, Rahbek C, Herman F, Hooghiemstra H, Hoorn C (2018) Geological and climatic influences on mountain biodiversity. Nature Geoscience 11(10): 718–725. https://doi.org/10.1038/s41561-018-0236-z
  • Atlas JE, Fu J (2019) Isolation by resistance analysis reveals major barrier effect imposed by the Tsinling Mountains on the Chinese wood frog. Journal of Zoology 309(1): 69–75. https://doi.org/10.1111/jzo.12702
  • Chen GX (1993) A study of the genus Tenuipotamon Dai 1990 from China. Sinozoologia 10: 75–85. [In Chinese with English summary]
  • Chu KL, Zhou LJ, Sun HY (2017) A new genus and new species of freshwater crab (Decapoda: Brachyura: Potamidae Ortmann, 1896) from Yunnan Province, China. Zootaxa 4286(2): 241–253. https://doi.org/10.11646/zootaxa.4286.2.7
  • Chu KL, Ma XP, Zhang ZW, Wang PF, Lv LN, Zhao Q, Sun HY (2018a) A checklist for the classification and distribution of China’s freshwater crabs. Biodiversity Science 26(3): 274–282. https://doi.org/10.17520/biods.2018062
  • Chu KL, Wang PF, Sun HY (2018b) A new genus and species of primary freshwater crab and a new species of Artopotamon Dai & Chen, 1985 (Crustacea, Brachyura, Potamidae) from western Yunnan, China. Zootaxa 4422(1): 115–131. https://doi.org/10.11646/zootaxa.4422.1.7
  • Crandall KA, Fitzpatrick Jr JF (1996) Crayfish molecular systematics: Using a combination of procedures to estimate phylogeny. Systematic Biology 45(1): 1–26. https://doi.org/10.1093/sysbio/45.1.1
  • Cumberlidge N, Ng PKL, Yeo DCJ, Naruse T, Meyer KS, Esser LJ (2011) Diversity, endemism and conservation of the freshwater crabs of China (Brachyura: Potamidae and Gecarcinucidae). Integrative Zoology 6(1): 45–55. https://doi.org/10.1111/j.1749-4877.2010.00228.x
  • Dai AY (1999) Fauna Sinica: Arthropoda Crustacea Malacostraca Decapoda Parathelphusidae Potamidae. Science Press, Beijing, China. [In Chinese with English summary]
  • Dai AY, Bo WF (1994) A new genus and three new species of freshwater crabs of Yuxi area of Yunnan Province (Crustacea: Decapoda: Brachyura: Potamidae). Memoirs of Beijing Natural History Museum 54: 21–28.
  • Dai AY, Naiyanetr P (1994) A revision of the genus Tiwaripotamon Bott, 1970, the freshwater crabs from China (Decapoda: Brachyura: Potamidae). Sinozoologia 11: 47–72.
  • Daniels RS, Phiri EE, Klaus S, Albrecht C, Cumberlidge N (2015) Multilocus phylogeny of the afrotropical freshwater crab fauna reveals historical drainage connectivity and transoceanic dispersal since the Eocene. Systematic Biology 64(4): 549–567. https://doi.org/10.1093/sysbio/syv011
  • Davie PJF, Guinot D, Ng PKL (2015) Anatomy and functional morphology of Brachyura. In: Castro P, Davie PJF, Guinot D, Schram F, Von Vaupel Klein C (Eds) Treatise on Zoology – Anatomy, Taxonomy, Biology – The Crustacea, Complementary to the Volumes Translated from the French of the Traité de Zoologie, 9(C)(I), Decapoda: Brachyura (Part 1), 11–163. https://doi.org/10.1163/9789004190832_004
  • Fang F, Ji YK, Zhao Q, Wang YJ, Gao W, Chu KL, Sun HY (2015) Phylogeography of the Chinese endemic freshwater crab Sinopotamon acutum (Brachyura, Potamidae). Zoologica Scripta 44(6): 653–666. https://doi.org/10.1111/zsc.12131
  • Huang C, Shih HT, Ng PKL (2017) A new genus and new species of Potamidea (Crustacea: Decapoda: Brachyura: Potamidae), the first stygomorphic cave crab known from China and East Asia. Zootaxa 4232(1): 071–084. https://doi.org/10.11646/zootaxa.4232.1.5
  • Huang C, Shih HT, Ahyong ST (2020a) The freshwater crab genus Lacunipotamon Dai, Song, He, Cao, Xu & Zhong, 1975 (Decapoda, Brachyura, Potamidae), with descriptions of two new species from southwestern China. Crustaceana 93(11–12): 1361–1379. https://doi.org/10.1163/15685403-bja10067
  • Huang C, Wang J, Shih HT (2020b) A new genus and two new species of freshwater crab (Crustacea: Brachyura: Potamidae) with unusual coiled tip of male second gonopods from Yunnan, southwestern China. Zoological Studies 59: 1–14. https://doi.org/10.6620/ZS.2020.59-24
  • Kalyaanamoorthy S, Minh BQ, Wong TK, von Haeseler A, Jermiin LS (2017) ModelFinder: Fast model selection for accurate phylogenetic estimates. Nature Methods 14(6): 587–589. https://doi.org/10.1038/nmeth.4285
  • Katoh K, Standley DM (2013) MAFFT multiple sequence alignment software version 7: Improvements in performance and usability. Molecular Biology and Evolution 30(4): 772–780. https://doi.org/10.1093/molbev/mst010
  • Kimura M (1980) A simple method for estimating evolutionary rate of base substitutions through comparative studies of nucleotide sequences. Journal of Molecular Evolution 16(2): 111–120. https://doi.org/10.1007/BF01731581
  • Kumar S, Stecher G, Li M, Knyaz C, Tamura K (2018) MEGA X: Molecular evolutionary genetics analysis across computing platforms. Molecular Biology and Evolution 35(6): 1547–1549. https://doi.org/10.1093/molbev/msy096
  • Li R, Kraft NJ, Yang J, Wang Y (2015) A phylogenetically informed delineation of floristic regions within a biodiversity hotspot in Yunnan, China. Scientific Reports 5(1): 1–7. https://doi.org/10.1038/srep09396
  • Myers N, Mittermeier RA, Mittermeier CG, Fonseca GA, Kent J (2000) Biodiversity hotspots for conservation priorities. Nature 403(6772): 853–858. https://doi.org/10.1038/35002501
  • Naruse T, Chia JE, Zhou XM (2018) Biodiversity surveys reveal eight new species of freshwater crabs (Decapoda: Brachyura: Potamidae) from Yunnan Province, China. PeerJ 6: e5497. https://doi.org/10.7717/peerj.5497
  • Ng PKL (1988) The freshwater crabs of Peninsular Malaysia and Singapore. Department of Zoology, National University of Singapore, Singapore.
  • Ng PKL (2017) Descriptions of two new cavernicolous species of Chinapotamon Dai & Naiyanetr, 1994 (Crustacea: Brachyura: Potamidae) from China. Crustacean Research 46(0): 1–16. https://doi.org/10.18353/crustacea.46.0_1
  • Nguyen LT, Schmidt HA, von Haeseler A, Minh BQ (2015) IQ-TREE: A Fast and Effective Stochastic Algorithm for Estimating Maximum-Likelihood Phylogenies. Molecular Biology and Evolution 32(1): 268–274. https://doi.org/10.1093/molbev/msu300
  • Pan D, Shi BY, Sun HY (2021a) A new species of freshwater crab of the genus Teretamon Yeo & Ng, 2007 (Decapoda, Brachyura, Potamidae) from southwestern Yunnan, China. Crustaceana 94(9): 1059–1070. https://doi.org/10.1163/15685403-bja10141
  • Pan D, Yeo DCJ, Sun HY (2021b) On a new species of freshwater crab of the genus Mekhongthelphusa Naiyanetr, 1994 (Decapoda: Brachyura: Gecarcinucidae) from south Yunnan, China. Nauplius 29: e2021050. https://doi.org/10.1590/2358-2936e2021050
  • Pan D, Shi BY, Du SY, Gu TY, Wang RX, Xing YH, Zhang Z, Cheng JJ, Cumberlidge N, Sun HY (2022) Mitogenome phylogeny reveals Indochina Peninsula origin and spatiotemporal diversification of freshwater crabs (Potamidae: Potamiscinae) in China. Cladistics 38(1): 1–12. https://doi.org/10.1111/cla.12475
  • Pan D, Sun HY, Ng PKL (2023) The identity of the freshwater crab Aiyunamon tumidum (Wood-Mason, 1871) (Brachyura, Potamidae), with description of a new species from China. Crustaceana 96(2): 179–198. https://doi.org/10.1163/15685403-bja10276
  • Rahbek C, Borregaard MK, Antonelli A, Colwell RK, Holt BG, Nogues-Bravo D, Rasmussen CM, Richardson K, Rosing MT, Whittaker RJ, Fjeldså J (2019) Building mountain biodiversity: Geological and evolutionary processes. Science 365(6458): 1114–1119. https://doi.org/10.1126/science.aax0151
  • Rambaut A, Drummond AJ, Xie D, Baele G, Suchard MA (2018) Posterior summarisation in Bayesian phylogenetics using Tracer 1.7. Systematic Biology 67(5): 901–904. https://doi.org/10.1093/sysbio/syy032
  • Ronquist F, Teslenko M, van der Mark P, Ayres DL, Darling A, Höhna S, Larget B, Liu L, Suchard MA, Huelsenbeck JP (2012) MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61(3): 539–542. https://doi.org/10.1093/sysbio/sys029
  • Shi BY, Pan D, Sun YF, Liu XR, Lv XL, Cumberlidge N, Sun HY (2021) Regional climates shape the biogeographic history of a broadly distributed freshwater crab species complex. Journal of Biogeography 48(6): 1432–1447. https://doi.org/10.1111/jbi.14088
  • Shi BY, Pan D, Sun HY (2022) A new genus and new species of potamid crab from Yunnan, southern China (Decapoda: Brachyura: Potamidae: Potamiscinae). Journal of Crustacean Biology 42(1): ruac001. https://doi.org/10.1093/jcbiol/ruac001
  • Tan QH, Zhou XJ, Zou JX (2021) Two new species of freshwater crab of the genus Aparapotamon Dai & Chen, 1985 (Crustacea, Brachyura, Potamidae) from Yunnan, China. ZooKeys 1056: 149–171. https://doi.org/10.3897/zookeys.1056.63755
  • Wang PF, Zhang ZW, Sun HY (2020) Ruiyupotamon, a new genus and four new species of freshwater crabs from northwestern Yunnan, China (Decapoda, Brachyura, Potamidae). Crustaceana 93(11–12): 1315–1341. https://doi.org/10.1163/15685403-bja10059
  • Wu S, Wang Y, Wang Z, Shrestha N, Liu J (2022) Species divergence with gene flow and hybrid speciation on the Qinghai–Tibet Plateau. The New Phytologist 234(2): 392–404. https://doi.org/10.1111/nph.17956
  • Ye XY, Ma PF, Yang GQ, Guo C, Zhang YX, Chen YM, Guo Z-H, Li D-Z (2019) Rapid diversification of alpine bamboos associated with the uplift of the Hengduan Mountains. Journal of Biogeography 46(12): 2678–2689. https://doi.org/10.1111/jbi.13723
  • Yeo DCJ, Ng PKL (2004) Recognition of two subfamilies in the Potamidae Ortmann, 1896 (Brachyura, Potamidae) with a note on the genus Potamon Savigny, 1816. Crustaceana 76: 1219–1235. https://doi.org/10.1163/156854003773123456
  • Zhang Z, Pan D, Hao X, Sun H (2020) Two new species of freshwater crabs of the genera Eosamon Yeo & Ng, 2007 and Indochinamon Yeo & Ng, 2007 (Crustacea, Brachyura, Potamidae) from southern Yunnan, China. ZooKeys 980: 1–21. https://doi.org/10.3897/zookeys.980.52186
  • Zou JX, Bai J, Zhou XM (2018) A new species of karst-dwelling freshwater crab of the genus Chinapotamon Dai & Naiyanetr, 1994 (Crustacea: Decapoda: Brachyura: Potamidae), from Guizhou, southwest China. PeerJ 6: e5947. https://doi.org/10.7717/peerj.5947
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