Parvuspotamon yuxiense Dai & Bo, 1994

Shi, Boyang, Pan, Da & Sun, Hongying, 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, pp. 13-38 : 13

publication ID	https://dx.doi.org/10.3897/zookeys.1183.109948
publication LSID	lsid:zoobank.org:pub:DA6935B9-D9E1-4B0B-8686-7B661CB9140E
DOI	https://doi.org/10.5281/zenodo.10170916
persistent identifier	https://treatment.plazi.org/id/3862E8BA-3793-579A-8CB6-B1B410E8B8ED
treatment provided by	ZooKeys by Pensoft
scientific name	Parvuspotamon yuxiense Dai & Bo, 1994
status

Treatment

Parvuspotamon yuxiense Dai & Bo, 1994 View in CoL

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 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. GoogleMaps • 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. GoogleMaps

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 View Figure 2 , 4A View Figure 4 ). Postorbital and epigastric cristae confluent (Figs 2A View Figure 2 , 4A View Figure 4 ); epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove (Figs 2A View Figure 2 , 4A View Figure 4 ); postorbital cristae low, indistinct (Figs 2A View Figure 2 , 4A View Figure 4 ). External orbital angle bluntly triangular, outer margin and anterolateral margin of carapace confluent (Figs 2A View Figure 2 , 4A View Figure 4 ). Anterolateral margin of carapace entire convex, smooth; posterolateral margin gently concave, smooth, converging towards posterior carapace margin (Figs 2A View Figure 2 , 4A View Figure 4 ). Epibranchial tooth indistinct (Figs 2A View Figure 2 , 4A View Figure 4 ). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital, sub-hepatic, and pterygostomial regions smooth (Figs 2B, C View Figure 2 , 4B, C View Figure 4 ). Antennular fossae slit-like in anterior view; median lobe of epistome posterior margin narrowly triangular (Figs 2B View Figure 2 , 4B View Figure 4 ). Third maxilliped with rhombus ischium; exopod reaching beyond anterolateral corner of ischium, without flagellum (Fig. 3G View Figure 3 ).

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

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

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 View Figure 2 , 3C, E View Figure 3 , 4C View Figure 4 ). Vulvae transversely ovate, widely located from each other, touching suture of sternites 5/6, posteromesial margin with low rim, opened obliquely upwards (Fig. 3F View Figure 3 ).

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 View Figure 2 , 3C View Figure 3 , 4C View Figure 4 ). Female pleon ovate, covering most of thoracic sternum (Fig. 3D View Figure 3 ).

G1 slender, reaching pleonal locking tubercle in situ, with terminal and subterminal segments clearly demarcated (Figs 3E, H, I View Figure 3 , 4D-G View Figure 4 ); subterminal segment stout, slightly sinuous (Figs 3H, I View Figure 3 , 4D, E View Figure 4 ); 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 View Figure 3 , 4D-G View Figure 4 ). G2 longer than G1; terminal segment relatively long; subterminal segment ~ 1.5 × length of terminal segment (Fig. 3J View Figure 3 ).

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.).