| Popis: |
Sylvathelphusa kalebi n. sp. (Figs. 2, 3) Type material. Holotype: male, cb 17.3 mm, cl 10.5 mm; allotype: female, cb 14.8 mm, cl 9.6 mm; paratype: male, cb 15.1 mm, cl 9.4 mm; La Pera nature reserve, 12 km NE of Berriozábal (16 ° 49 ' 53 " N, 93 ° 17 ' 42 " W; 1178 m), Municipio de Tuxtla Gutiérrez, Chiapas, Mexico; 12 Sep 2008; colls: K. Zárate, I.A. Córdoba, A.J. Flores, C.A. Pérez, G. Salinas; CNCR 26179. Other material examined (non-types). 5 males, cb 12.0- 15.5 mm, cl 7.8-10.5 mm; 2 females 15.0 mm both, cl 9.2-9.5 mm; same locality as holotype; 27 Nov 2008; colls: J.L. Villalobos, C. Hernández, K. Zárate, A. García, C. Enríquez, E. Torres; CNCR 26181. Description. Small sized crabs (cb Eyes with cornea pigmented, faintly faceted, not filling orbits (Fig. 2 d). Epistome narrow, epistomial tooth low, triangular, slightly deflexed, borders smooth (Fig. 2 c). Suborbital, subhepatic and pterygostomian regions pubescent. Third maxilliped with ratio exopod/ischium 0.47, ischium with outer margin slightly sinuous, inner margin straight, external margin of merus widely curved (Fig. 2 c). Aperture of efferent branchial channel subrectangular. Chelipeds subequal in size and shape; merus subtriangular in cross section, 4.3 times as long as wide, superior internal border with row of conical and acute spines, increasing in size distally, alternating with small spinules. Carpus smooth, prominent and acute subdistal spine on inner side. Chela slender (length/height 3.6), surface smooth, with faint minute teeth on upper and lower rounded borders. Fingers slender, as long as palm, not gaping, tips crossing; both fingers with sharp triangular teeth on cutting edges, becoming smaller distally; dactylus with alternating large and small teeth (Fig. 2 b). Thoracic sternites of third maxillipeds and first pereiopods completely fused, except for small notches at lateral edges of sternum; sternal sulci s 4 /s 5, s 5 /s 6 and s 6 /s 7 distinct, just failing to reach midline of thoracic sternum. All abdominal segments free. Telson subtriangular, narrow; lateral margins distinctly straight, tip rounded. Male gonopod not completely chitinized, latero-mesially compressed, slightly arched in caudal and cephalic views, distal half wider. In mesial view, marginal suture almost straight along most of gonopod, slightly concave in middle (Fig. 3 a). Marginal plate between caudal and mesial surfaces, without marginal setae basally; distal half widening distally, ending in triangular apical projection overreaching mesial process, lying on caudal margin of apical projection, ending in acute distal margin with triangular tubercle (Fig. 3 a). Caudal portion of marginal plate limited by lateral suture, distal third rounded. Mesial surface ending in tongue-like apical projection, distocephalically directed, longer than apical projection of marginal plate, distal margin broad, rounded, sculptured with shallow longitudinal grooves and scattered subacute granules (Fig. 3 a). Mesial process as triangular, stout, acute spine, directed cephalad, forming 90 º angle with respect to principal axis of gonopod (Fig. 3 a). Caudal surface with medial shallow, rounded notch. Lateral suture visible through proximal two thirds, apically separating marginal plate from caudal surface. In cephalic view, mesial process conical, stout, acute (Fig. 3 b). Lateral surface with small triangular distomedial tubercle (Fig. 3 b); distal third of laterocaudal portion forming high, rounded border, with central depression (Fig. 3 b). Distal end of marginal plate subacute. In lateral view, caudal surface with medial constriction (Fig. 3 c). Lateral surface becoming broader caudally, forming on distal third ample plate with high caudal margin, laterally directed (Fig. 3 c). Deep suture at base of apical projection of mesial surface, separating lateral and mesial plates (Fig. 3 c). In caudal view, gonopod slightly arched laterally (Fig. 3 d). Distal half with lateral margin expanded, with low, distal, triangular prominence (Fig. 3 d). In apical view, apical portion of marginal plate ending in acute tip (Fig. 2 e). Mesial surface with broad, rounded distal margin, with few granules (Fig. 2 e). Mesial process conical, stout, acute, directed cephalically (Fig. 2 e). Apical cavity covered by hood formed by distal crest of lateral surface. Opening of spermatic channel located caudally (Fig. 2 e). Color in life. Carapace dark olive or gray, chelipeds white and ambulatory legs light brown, thoracic sternites and abdomen light yellow. Etymology. The species is named after Kaleb Zárate, biologist and speleologist, who first discovered this population. Remarks. This is the first record of a completely terrestrial pseudothelphusid crab in Mexico, although Pseudothelphusa parabelliana Álvarez, 1989, Odontothelphusa maxillipes (Rathbun, 1898), Potamocarcinus magnus (Rathbun, 1895) and Raddaus bocourti (A. Milne-Edwards, 1866), have been observed at considerable distances from the nearest stream. The crabs representing the new species were found in a tropical rainforest NE of the town of Berriozábal, at altitudes ranging from 950 to 1200 m. They were found under limestone in crevices, where the soil is humid and contains abundant organic matter composed of leaf litter in different stages of decomposition. No streams, rivers or other aquatic bodies were observed nearby. |
