Cantopotamon zhuhaiense, 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 : 3-6

publication ID	https://doi.org/ 10.6620/ZS.2017.56-41
persistent identifier	https://treatment.plazi.org/id/9B11878D-FFC8-FFE6-44EB-B0F5FAF6FE00
treatment provided by	Felipe
scientific name	Cantopotamon zhuhaiense
status	sp. nov.

Treatment

Cantopotamon zhuhaiense View in CoL n. sp.

( Figs. 1-2 View Fig View Fig , 9A View Fig , 10A View Fig , 11A View Fig , 12A View Fig )

urn:lsid:zoobank.org:act:003D5AB3-EBF6-4BB1-80AA-F77A7A1415F9

Type material: Holotype: SYSBM 001438 , male (29.1 × 22.9 mm), Xiangzhou (22.25°N, 113.56°E), Zhuhai City, Guangdong, small hillstreams, under rocks, coll. C. Huang, July, 2013 GoogleMaps . Paratypes: SYSBM 001440, 1 female (24.6 × 20.0 mm), same data as holotype. SYSBM 001439, 1 male (24.1 × 20.1 mm), same data as holotype, SYSBM 001441, 1 female (22.3 × 17.3 mm), same data as holotype.

Other material examined: SYSBM 001425, 1 male (30.2 × 24.0 mm), Xiangzhou, Zhuhai City, Guangdong, small hillstreams, under rocks, coll. C. Huang, March, 2012. SYSBM 001426, 1 female (17.8 × 14.5 mm), same as above male; ZRC, 1 male, 2 females, Xiangzhou, Zhuhai City, Guangdong, June 2011.

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

Diagnosis: Third maxilliped merus width about 1.2 × length; ischium width about 0.77 × length ( Figs. 1B View Fig , 2D View Fig ). Major cheliped palm length about 1.3 × height ( Fig. 1A View Fig ). Male pleonite 6 width about 2.2 × length; telson width about 1.2 × length ( Fig. 1C View Fig ). Tip of G1 terminal segment not reaching tubercle forming pleonal locking structure, scarcely exceeding sternite 5/6 suture ( Fig. 1D View Fig ); subterminal segment length about 2.2 × length of terminal segment, inner proximal section curved dorsally; terminal segment inner margin broadly triangular, tip cone-shaped ( Figs. 1D View Fig , 2B, C View Fig , 9A, B View Fig ). G2 about 2.6 × length of flagelliform distal segment ( Fig. 2A 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. 1A View Fig ). Front slightly deflexed, margin slightly ridged on dorsal view ( Fig. 1A View Fig ). Epigastric cristae distinct, separated by narrow gap ( Figs. 1A, B View Fig ). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth ( Figs. 1A, B View Fig ). Branchial regions relatively flat ( Fig. 1A View Fig ). Cervical groove shallow, inconspicuous ( Fig. 1A View Fig ). Mesogastric region slightly convex ( Fig. 1A View Fig ). External orbital angle triangular ( Fig. 1A View Fig ). Epibranchial tooth small, granular, but distinct ( Fig. 1A, B View Fig ). Anterolateral margin distinctly cristate, lined with approximately 16-18 granules; lateral part bent inward ( Fig. 1A View Fig ). Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin ( Fig. 1A View Fig ). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous granules ( Fig. 1B View Fig ). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules; sub-hepatic region lined with oblique striae ( Fig. 1B View Fig ).

Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight ( Fig. 1B View Fig ).

Third maxilliped merus width about 1.2 × length; ischium width about 0.8 × 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. 1B View Fig , 2D View Fig ).

Chelipeds (pereopod 1) unequal ( Fig. 1A View Fig ). Merus cross-section trigonal; margins crenulated ( Fig. 1B View Fig ). Carpus with sharp distomesial spine and spinule at base; dorsal surface with curved striae ( Fig. 1A View Fig ). Major cheliped palm length about 1.3 × height ( Fig. 1A View Fig ). Movable finger as long as fixed finger ( Fig. 1A View Fig ). Occlusal margin of fingers with rounded, blunt teeth; with gape when closed ( Fig. 1A View Fig ).

Ambulatory legs slender (pereopods 2-5); dactylus with dense, short setae; propodus, carpus and merus with relatively sparse, short, setae ( Fig. 1A View Fig ). Pereopod 5 propodus about 2 times as long as broad, about as long as dactylus ( Fig. 1A View Fig ).

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

Male pleon triangular, almost reaching anteriorly to level of posterior margin of cheliped coxae; somites 3-6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2.2 × length; telson width about 1.2 × length; apex rounded ( Fig. 1C View Fig ).

G1 generally slender, relatively short, tip of terminal segment not reaching tubercle forming pleonal locking structure, barely exceeding sternite 5/6 suture ( Fig. 1D View Fig ); subterminal segment length about 2.2 × length of terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted (on left G1), curved inwards and pointing anteriorly, inner margin broadly triangular, tip cone-shaped ( Figs. 1D View Fig , 2B, C View Fig , 9A, B View Fig ). G2 basal segment subovate, about 2.6 × length of flagelliform distal segment ( Fig. 2A View Fig ).

Size range: Male (n = 3) 24.1 × 20.1 to 30.2 × 24.0 mm; female (n = 3) 17.8 × 14.5 to 24.6 × 20.0 mm.

Remarks: Cantopotamon zhuhaiense n. sp. is closest to C. shangchuanense n. sp. and C. hengqinense n. sp. in overall external morphology, but can be distinguished by its shorter G1 that does not the reach tubercle of the pleonal locking structure in situ ( Fig. 1D View Fig ) [versus long G1 that reaches beyond in both C. shangchuanense n. sp. ( Fig. 3D View Fig ) and C. hengqinense n. sp. ( Fig. 5D View Fig )]; broadly triangular inner margin of G1 terminal segment ( Fig. 2C View Fig ) [versus convex in C. shangchuanense n. sp. ( Fig. 4C View Fig ) and sinuous in C. hengqinense n. sp. (6C)]; and other characters as shown in table 2.

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

Ecology: This species is mainly aquatic, living under rocks in small hillstreams. At its type locality, C. zhuhaiense is sympatric with Nanhaipotamon cf. guangdongense Dai, 1997 and Nanhaipotamon zhuhaiense Huang, Huang & Ng, 2012 . One individual, still moving, was observed within the grasp of a Nanhaipotamon cf. guangdongense in the latter’s mud burrow, suggesting they are at least occasional prey items of Nanhaipotamon .

Distribution: Xiangzhou, Zhuhai, Guangdong.