Tzotzilthelphusa villarosalensis, Villalobos, José Luis & Álvarez, Fernando, 2013

Villalobos, José Luis & Álvarez, Fernando, 2013, Two new genera and three new species of freshwater crabs (Crustacea: Pseudothelphusidae: Potamocarcinini) from Chiapas, Mexico, Zootaxa 3599 (5), pp. 457-470 : 467

Tzotzilthelphusa villarosalensis n. sp.

( Figs. 6 , 7 )

Type material. Holotype: male, cb 31.2 mm, cl 20.9 mm; ditch along highway 101 near Villa de las Rosas (16º21'0.5" N, 92º23'59.07" W; 1152 m), Municipio de Villa de las Rosas, Chiapas, Mexico; 3 Dec. 2007; coll. F. Álvarez, J.L. Villalobos, A. Botello, C. Hernández; CNCR 26192. Allotype: female, cb 24.8 mm, cl 16.8 mm,; same locality as holotype, 30 Apr 2009; coll. F. Álvarez, J.L. Villalobos, G. Armendáriz, E. Torres; CNCR 25385. Paratypes: 4 males, cb 32.5-21.0 mm, cl 21.0- 18.7 mm; 3 females, cb 21.9- 19.7 mm, cl 15.0- 13.4 mm; same locality, date and collectors as allotype; CNCR 27339.

Description. In dorsal view carapace moderately oval, widest in middle (cb/cl = 1.63); dorsal surface convex, punctated, regions faintly indicated, cephalic and branchial somewhat elevated; pair of gastric pits barely distinct, oblique, narrowly elongated; cervical grooves wide, shallow, arched, not reaching anterolateral margin ( Fig. 6 a). Postfrontal lobes and median groove discernible. Frontal region curved downwards to frontal border; superior frontal border absent, inferior one smooth, projected, divided into 2 low convex lobes, separated by rounded medial depression ( Fig 6 d). Superior orbital margin continuous with frontal border; inferior orbital margin marked by row of rounded granules; exorbital angle flat. Anterolateral margin smooth along anterior third, granulated on branchial region, straight through posterior half. Posterior margin concave.

Eyes with cornea normally faceted, pigmented, filling orbits. Epistome narrow; epistomial tooth low, triangular, deflexed, borders smooth. Suborbital and subhepatic regions of carapace smooth, punctated; pterygostomial region pubescent around mouthparts. Third maxilliped with ischium rectangular, merus with external margin widely rounded, ratio exopod/ischium 0.9 ( Fig. 6 c). Aperture of efferent branchial channel subquadrate.

Chelipeds different in shape and size. Major cheliped with merus subtriangular in cross section, short, thick, shorter than carapace length, dorsal surface smooth; internal dorsal margin with row of acute granules; external margin delimited by rounded granules on proximal two-thirds. Carpus smooth with small, low tubercles on internal margin. Palm compressed, high (length/high = 1.3); fingers longer than palm, stout, smooth, not gaping, with low, triangular teeth on cutting edges ( Fig. 6 b). Thoracic sternites of third maxilliped and first pereiopod completely fused, except for short fissures at lateral edges of sternum; sternal sulci s4/s5, s5/s6 and s6/s7 distinct, just failing to reach midline of thoracic sternum; sternal sulcus s7/s8 reaching midline. All abdominal segments free. Telson subtriangular, lateral margins straight, tip rounded.

First male gonopod as described under genus diagnosis.

Etymology. The specific name is derived from "Villa de las Rosas" the name of the closest town to the type locality in Chiapas, Mexico.

Remarks. Tzotzilthelphusa villarosalensis n. sp. has a gonopod with the distal third bent laterally, but without torsion. The apical cavity of the gonopod is oblique to the principal axis of the gonopod due to the elevation of the mesial surface. The gonopod morphology of the new species is similar to that of Typhlopseudothelphusa hyba , raising an interesting problem because that species was placed in Typhlopseudothelphusa due to its external morphology, which is very similar to that of T. mocinoi . However, considering the gonopod morphology T. hyba could be placed in Tzotzilthelphusa n. gen., a problem that will have to be addressed in the future. Geographically, T. hyba and T. villarosalensis n. sp. are only 40 km apart to the south of San Cristóbal de las Casas.

Figures

FIGURE 6. Tzotzilthelphusa villarosalensis n. sp., male holotype. a, dorsal view; b, major chela; c, third maxillipeds; d, frontal portion of carapace; e, apical view of gonopod. Abbreviations: map, marginal process; mep, mesial process; mes, mesial surface; osp, opening of spermatic channel.

FIGURE 7. Tzotzilthelphusa villarosalensis n. sp., male holotype. Left first gonopod: a, mesial view; b, cephalic view; c, lateral view; d, caudal view. Abbreviations: ac, apex cavity; map, marginal process; mas, marginal suture; mep, mesial process; mes, mesial surface.