Trichopotamon xiangyunense, Naruse, Tohru, Yeo, Darren C. J. & Zhou, Xianmin, 2008

Naruse, Tohru, Yeo, Darren C. J. & Zhou, Xianmin, 2008, Five new species of freshwater crabs (Crustacea: Decapoda: Brachyura: Potamidae) from China, Zootaxa 1812, pp. 49-68 : 63-66

Trichopotamon xiangyunense spec. nov.

( Figs. 13–15 )

Material examined. Holotype: male, 21.0× 25.7 mm, NCU MCP 2008.0008, Xiangyun County (ca. 25°28’32’’N 100°32’54’’E), Yunnan Province, coll. Xue L¸ & Xianmin Zhou, 31 Jul. 2005.

Paratypes: 2 males, 17.3×21.0, 20.0× 24.9 mm, 6 females, 18.3×22.8–24.1× 30.2 mm, NCU MCP 2008.0009, data same as holotype; 3 males, 18.6×22.8–21.0× 26.3 mm, 2 females, 24.7×30.5, 25.4× 31.7 mm, ZRC 2008.0016, data same as holotype; 1 male, 18.6× 22.9 mm, 3 females, 18.6×23.4–25.6× 31.6 mm, NMNS-5753-001, data same as holotype.

Description. Carapace ( Fig. 13 a) broader than long, widest across middle of anterolateral margins, CW 1.21–1.27 times (mean 1.24, n = 13) CL; sidewall relatively high, dorsal surface convex longitudinally, transversely, smooth, regions distinctly demarcated by grooves; epigastric crista raised, postorbital crista raised, distinct, reaching cervical groove laterally, H-shaped gastric groove, mesogastric region distinct. Front deflexed distally, slightly concave medially, median part of anterior margin produced ventrally, embracing proepistome. Supra-, infraorbital margins ( Fig. 13 b) cristate, infraorbital margin lined with low granules; suborbital region smooth, pterygostomial region granulated. External orbital angle almost right angle, directed anteriorly, outer margin about 1.5 times longer than inner margin; epibranchital tooth distinct, disconnected from external orbital angle by narrow gap, anterolateral margin cristate, lined with small granules, convex, shorter than posterolateral margin. Antennular fossa compressed pentagonal; epistome with posterior margin cristate, lined with granules except for concave outer third, with median long, triangular lobe.

Palp of mandible three-segmented, with terminal segment simple. Third maxilliped ( Figs. 13 b, 14) rectangular, midlength of ischium about 2 times that of merus, exopod reaching proximal quarter of outer margin of merus, flagellum vestigial.

Thoracic sternites 2, 3 ( Fig. 14 ) demarcated by distinct suture. Abdominal cavity reaching imaginary line joining posterior two-fifths of cheliped coxae, cavity relatively narrow, distance between inner ends of sutures between thoracic sternites 4, 5 larger than third length of distance between sternal condyles; sternal condyle on middle of thoracic sternite 5; thoracic sternite 8 demarcated medially by uninterrupted longitudinal median line, without transverse ridge at inner ends of sutures between thoracic sternites 7, 8.

Chelipeds ( Fig. 13 a) similar in males, major cheliped slightly stouter; merus granulated on dorsal, ventral margins, subdistal dorsal tooth largest, ventral subdistal tooth low; carpus with strong inner angle, lower tooth absent; palm with convex outer surface, height slightly longer than length; fingers slightly shorter than palm, gape narrow when chela closed, cutting edge lined with regularly placed large teeth, fringed with low teeth between them.

Ambulatory legs long, with scattered short setae, second longest when stretched laterally; merus with low subdistal angle on anterior margin; dactyli longer than respective propodi.

Abdomen, telson ( Fig. 14 ) triangular, first abdominal segment with transverse ridge; third segment widest, lateral margins of third segment to telson forming almost straight line; telson triangular, width 1.12–1.26 times length (mean = 1.19, n = 2), 1.15–1.50 times (mean = 1.33, n = 2) longer than sixth segment, sixth segment width 2.1–2.4 times length (mean = 2.24, n = 2). G1 stout, straight, setose distally; proximal outer angle of subterminal segment distinct; ventral-outer layer with longitudinal suture along inner margin; subterminal, terminal segments demarcated by membrane-like suture, membrane narrow from longitudinal suture of ventral outer layer to outer part of dorsal side, membrane widened inwards on dorsal side, subdistal inner margin, proximal part of membrane produced inwards; distal segment about two-thirds length of subdistal segment in ventral view, groove for G2 close to inner layer in ventral view, but inner layer always visible in ventral view, distal outer margin of distal segment notched. G2 ( Fig. 15 c) slightly longer than G1, flagellum ribbon-like, about three-quarters of narrowed part of basal segment.

Distribution and habitat. Trichopotamon xiangyunense spec. nov. is known only from the type locality (Xiangyun County, Yunnan Province, China; 2012 m asl.). The species was found in a rivulet with depth of about 30 cm with sandy substratum. The water temperature is about 19°C, and its pH was 6.0.

Remarks. Trichopotamon xiangyunense spec. nov. can be distinguished from its only congener, T. daliense Dai & Chen, 1985 , by the morphology of the G1. In T. xiangyunense the inner margin of the G1 has two medial triangular projections; the distal projection is larger and represents an inner margin of a membrane-like structure of the dorsal side, and another proximal smaller projection is located just proximal to the membrane like-structure ( Fig. 15 b). In T. xiangyunense , however, the inner margin of the membrane-like structure is just slightly convex laterally and it is much lower than proximal projection [ Dai & Chen 1985: Fig. 6 (6)]. Furthermore, the subterminal segment of the G1 of T. xiangyunense is narrower than that of T. daliense [ Fig. 15 a: Dai & Chen 1985: Fig. 6 (4, 5); Dai 1999: Fig. 198(4)].

Figures

FIGURE 6. Male gonopods of Latopotamon qujingense spec. nov. (holotype male, 18.4 × 23.1 mm). a, left G 1, ventral view; b, distal segment of left G 1, vento-outer view; c, distal segment of left G 1, dorso-inner view; d, left G 2. Scales, 1 mm.

FIGURE 13. Trichopotamon xiangyunense spec. nov. (holotype male, 21.0 × 25.7 mm). a, habitus, dorsal view; b, cephalothorax, anterior view.

FIGURE 14. Ventral view of Trichopotamon xiangyunense spec. nov. (holotype male, 21.0 × 25.7 mm).

FIGURE 15. Male gonopods of Trichopotamon xiangyunense spec. nov. (paratype male, 19.6 × 24.9 mm). a, left G 1, ventral view; b, distal segment of left G 1, dorsal view; c, G 2. Scale, 1 mm.