Cantopotamon shangchuanense, Huang & Ahyong & Shih, 2017

Huang, Chao, Ahyong, Shane T. & Shih, Hsi-Te, 2017, , A New Genus of Freshwater Crabs from Guangdong, China, with Descriptions of Four New Species (Crustacea: Decapoda: Brachyura: Potamidae)., Zoological Studies 56 (41), pp. 1-20 : 6-9

publication ID	https://doi.org/ 10.6620/ZS.2017.56-41
persistent identifier	https://treatment.plazi.org/id/9B11878D-FFCF-FFEB-4421-B2A8FC6EFDA0
treatment provided by	Felipe
scientific name	Cantopotamon shangchuanense
status	sp. nov.

Treatment

Cantopotamon shangchuanense View in CoL n. sp.

( Figs. 3-4 View Fig View Fig , 9B View Fig , 10B View Fig , 11B View Fig , 12B View Fig )

urn:lsid:zoobank.org:act:214D7745-AB4C-4A3D-862B-9C1D57BA4301

Type material: Holotype: SYSBM 001427 , male (24.1 × 19.5 mm), Shangchuan island (21.63°N, 112.78°E), Taishan City, Guangdong, small hillstreams, under rocks, coll. C. Huang, March, 2015 GoogleMaps . Paratypes: SYSBM 001429, 1 female (17.3 × 14.1 mm), same data as holotype. SYSBM 001428, 1 male (21.0 × 17.2 mm), same data as holotype, SYSBM 001430, 1 female (14.8 × 11.9 mm), same data as holotype.

Etymology: This species is named after the type locality, Shangchuan Island, Taishan City, Guangdong Province, China.

Diagnosis: Third maxilliped merus width about 1.2 × length; ischium width about 0.71 × length ( Figs. 3B View Fig , 4D View Fig ). Major cheliped palm length about 1.2 × height ( Fig. 3A View Fig ). Male pleonite 6 width about 2.3 × length; telson width about 1.4 × length ( Fig. 3C View Fig ). Tip of G1 terminal segment reaching well beyond tubercle forming pleonal locking structure, exceeding sternite 4/5 suture ( Fig. 3D View Fig ); subterminal segment about 2.5 times as long as terminal segment, inner proximal section curved dorsally; terminal segment inner distal margin strongly convex, tip blunt ( Figs. 3D View Fig , 4B, C View Fig , 9C, D View Fig ). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment ( Fig. 4A View Fig ).

Description of male: Carapace broader than long, regions indistinct; dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region ( Fig. 3A View Fig ). Front slightly deflexed, margin slightly ridged on dorsal view ( Fig. 3A View Fig ). Epigastric cristae distinct, separated by narrow gap ( Figs. 3A, B View Fig ). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth ( Figs. 3A, B View Fig ). Branchial regions slightly swollen ( Fig. 3A View Fig ). Cervical groove shallow, inconspicuous ( Fig. 3A View Fig ). Mesogastric region slightly convex ( Fig. 3A View Fig ). External orbital angle triangular ( Fig. 3A View Fig ). Epibranchial tooth small, granular, but distinct ( Figs. 3A, B View Fig ). Anterolateral margin distinctly cristate, lined with approximately 17-19 granules; lateral part bent inward ( Fig. 3A View Fig ).

Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin ( Fig. 3A View Fig ). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous granules ( Fig. 3B View Fig ). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules, sub-hepatic region lined with oblique striae ( Fig. 3B View Fig ).

Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight ( Fig. 3B View Fig ).

Third maxilliped merus width about 1.2 × length; ischium width about 0.7 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus; exopod reaching to proximal one-third of merus, flagellum long; dorsomesial margin of ischium subauriculiform ( Figs. 3B View Fig , 4D View Fig ).

Chelipeds (pereopod 1) unequal ( Fig. 3A View Fig ). Merus cross-section trigonal; margins crenulated ( Fig. 3B View Fig ). Carpus with sharp distomesial spine and spinule at base, dorsal surface with curved striae ( Fig. 3A View Fig ). Major cheliped palm length about 1.2 × height ( Fig. 3A View Fig ). Movable finger as long as fixed finger ( Fig. 3A View Fig ). Occlusal margin of fingers with rounded, blunt teeth; with very small gape when closed ( Fig. 3A View Fig ).

Ambulatory legs (pereopods 2-5) slender, with dense short setae on dactylus, relatively sparse short setae on the propodus, carpus and merus ( Fig. 3A View Fig ). Pereopod 5 with propodus about 2 times as long as board, subequal to dactylus ( Fig. 3A View Fig ).

Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused without obvious median suture ( Figs. 3C View Fig , 10B View Fig ). Male sterno-pleonal cavity reaching anteriorly to midlength of cheliped coxae; median longitudinal groove between sternites 7/8 deep ( Fig. 3D View Fig ). Pleonal locking tubercle slightly posterior to mid-length of sternite 5 ( Fig. 3D View Fig ).

Male pleon triangular, almost reaching anteriorly to level of posterior margin of cheliped coxae; pleonites 3-6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2.3 × length; telson width about 1.4 × length, apex rounded ( Fig. 3C View Fig ).

G1 tip of terminal segment reaching well beyond tubercle forming pleonal locking structure, exceeding sternite 4/5 suture ( Fig. 3D View Fig ); subterminal segment about 2.5 times as long as terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted (on left G1), curved inwards and pointing anteriorly, inner distal margin strongly convex, tip blunt ( Figs. 3D View Fig , 4B, C View Fig , 9C, D View Fig ). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment ( Fig. 4A View Fig ).

Size range: Male (n = 2) 21.0 × 17.2 to 24.1 × 19.5 mm; female (n = 2) 14.8 × 11.9 to 17.3 × 14.1 mm.

Remarks: Cantopotamon shangchuanense n. sp. is close to C. zhuhaiense n. sp., in overall external morphology, but can be separated by a unique combination of characters as shown in the Remarks section for C. zhuhaiense n. sp. and table 2.

Colour in life: Mottled brown overall ( Fig. 12B View Fig ).

Ecology: This species is mainly aquatic, living under rocks in small hillstreams. The hillstream in which it was found drains directly to the sea, with Eriocheir sp. also inhabiting the lower reaches. The species of Eriocheir was not confirmed, but given the location, it was probably E. hepuensis (see Naser et al. 2012). No other potamids where found at the type locality.

Distribution: Shangchuan Island, Taishan, Guangdong.