Neostrengeria lassoi, Campos, Martha R., 2017

Campos, Martha R., 2017, Two new species of freshwater, cave-dwelling crabs of the genus Neostrengeria Pretzmann, 1965, from Colombia (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 4247 (2), pp. 157-164 : 161-164

Neostrengeria lassoi n. sp.

( Figs. 2 , 3 )

Holotype. Male (cl 12.6 mm, cb 21.0 mm), ICN-MHN-CR 3174, Municipio La Guadalupe, Los Aviones cave, elevation 1555 m, Santander Department , Colombia, 6°13.4’4.4” N 73°25’8.4” W, 17 Jun 2016, leg. C. A. Lasso.

Paratypes. Two males (cl 12.5, and 12.4 mm, cb 21.0, and 20.3 mm, 1 juvenile), ICN-MHN-CR 3175, 1 male (cl 11.5 mm, cb 19.0 mm), IAvH-I-1193. Same data as for holotype .

Diagnosis. Male first gonopod wider in mid-distal portion; mesial side forming convex expansion in mid portion with subdistal protuberance, small lobe distally; marginal suture nearly straight, distally rounded, fringed with 4 acute spines; lateral lobe semicircular, external margin rounded, internal margin straight, with distal portion directed distally; accessory lobe wide, oblong, bent into caudo-cephalic direction, distally rounded, internal margin with subdistal notch, separated from accessory lobe by wide depression; accessory lobe slightly shorter than lateral lobe; apex outline oblong in distal view, with 4 acute spines on caudal border, lateral border projected into concave expansion, cephalic border slightly sinuous, mesial lobe triangular; mesio-caudal projection of spermatic channel bifid, with distal papillae; spermatic channel with conspicuous rows of spinules ( Fig. 4 E). Exognath of third maxilliped between 0.56, 0.59 length of ischium of endognath.

Description of the holotype. Carapace ( Fig. 3 A) with cervical groove straight, narrow, shallow anteriorly, deep, wide posteriorly, ending some distance from lateral margin; anterolateral margin with shallow sinus posterior to antero-external orbital angle, fringed with tubercles, 4 papillae anterior of cervical groove, lateral margin with approximately 20 rounded papillae; posterior margin smooth; postfrontal lobes oval, delimited anteriorly by 2 depressions; median groove wide, shallow, without incision on upper border of front; front with upper border rounded, not demarcated, bilobed in dorsal view, surface of front between upper, lower borders narrow, vertical, lower border sinuous in frontal view, fringed with tubercles, slightly protruding with respect to upper border in dorsal view; orbital margins each with row of rounded tubercles, eyes large, filling the orbits, cornea well developed, pigmented ( Fig. 3 A, B); dorsal surface of carapace smooth, covered by small papillae, regions distinctly marked. Third maxilliped with sternal margin of merus bearing strongly rounded lobe after mid portion, followed by subdistal notch. Exognath 0.58 the length of ischium ( Fig. 4 F). Efferent branchial channel open, trapezoidal ( Fig. 3 B).

First pereopods heterochelous ( Fig. 1 A, B); right cheliped slightly larger than left; merus with 3 crests: upper crest with rows of rounded tubercles, internal lower crest with row of 11 acute teeth, increasing in size distally, external lower crest with row of blunt tubercles; carpus with 5 semi-acute spines, distal one prominent, rounded; palms of both chelipeds smooth, palm of larger cheliped strongly swollen, fingers not gaping when closed, smaller cheliped slightly swollen, fingers not gaping when closed, outer, inner surfaces of fingers of both chelae with rows of small tubercles, fingers with intercalated large, small subtriangular teeth. Walking legs (second to fifth pereopods) slender, dactyli each about 1.4 times as long as propodi, with 5 longitudinal rows of large spines diminishing in size proximally. Spines, papillae on each dactylus arranged as follows: antero-lateral row, anteroventral row each with 5 spines, 2 proximal papillae; external row with 4 spines, 3 intercalated papillae; posteroventral row, postero-lateral row each with 4 spines.

Male first gonopod wider in mid-distal portion, bent distally towards cephalic side in lateral, mesial views; mesial side forming convex expansion in mid portion with subdistal protuberance, small lobe distally; marginal suture nearly straight, distally rounded, fringed with 4 acute spines, proximal portion forming rounded lobe with conspicuous long setae; lateral lobe semicircular, external margin rounded, internal margin straight, with distal portion directed distally, separated from accessory lobe by wide depression; accessory lobe wide, oblong, bent into caudo-cephalic direction, distally rounded, internal margin with subdistal notch; accessory lobe slightly shorter than lateral lobe ( Fig. 4 A, B); apex outline oblong in distal view, with 4 acute spines on caudal border; lateral border projected into concave expansion, cephalic border slightly sinuous, mesial lobe triangular; mesio-caudal projection of spermatic channel bifid with distal papillae; spermatic channel with conspicuous rows of spinules ( Fig. 4 E).

Color. The alcohol-preserved holotype is mottled brown (near Vandyke Brown, 121; Smithe, (1975)) on the dorsal side of the carapace. The walking legs are mottled brown (near Prout Brown, 121A) dorsal, light brown (near Mikado Brown, 121C) ventrally. The chelae are brown (near Brussels Brown, 121B) dorsal, light brown (near Mikado Brown, 121C) ventrally. The ventral surface of the carapace is mottled brown (near Brussels Brown, 121B).

Habitat. Some of the specimens were collected near a waterfall outside of the cave and the others in a stream inside the cave. They were hand-collected.

Etymology. The species is dedicated to the Spanish-Venezuelan biologist Carlos A. Lasso (Alexander von Humboldt Institute), a very active researcher working on terrestrial and aquatic ecosystems, and who collected the specimens.

Remarks. Comparison with descriptions and with material of other species reveals that Neostrengeria lassoi sp. n. is most similar to Neostrengeria niceforoi (Schmitt, 1969) . The main distinguishing feature between both species is the form of the first gonopod. The male first gonopod of N. niceforoi has been described and illustrated by Campos (2005: 203, fig. 59; 2014: 534, fig. 204). In N. lassoi the mesial side forms a convex expansion in mid portion, with a protuberance subdistally and small lobe distally, whereas in N. niceforoi it is strongly convex, with mid depression and small semi-acute protuberance subdistally. The lateral lobe in N. niceforoi is elongated, foliose, nearly circular, with distal portion directed laterally, whereas in N. lassoi it is semicircular, with external margin rounded, internal margin straight, and distal portion directed distally. The caudo-lateral border of the apex in N. niceforoi has 8¯10 conspicuous, acute spines, the cephalic border shows two cephalic spines separated to each other by deep depression, the mesio-caudal projection of spermatic channel has an internal papilla and external acute spinule; in contrast, N. lassoi presents only four acute spines on the caudal border, the cephalic border is devoid of spines, and the mesio-caudal projection of spermatic channel is bifid and ends in papillae.

Figures

FIGURE 1. Neostrengeria fernandezi new species, holotype male, ICN-MHN-CR 3172. A, dorsal view of carapace; B, ventral view of carapace.

FIGURE 2. Neostrengeria fernandezi n. sp., holotype male, ICN-MHN-CR 3172. A, left first gonopod, caudal view; B, same, lateral view; C, same, cephalic view; D, same, mesial view; E, same, detail of apex, distal view; F, left third maxilliped, external view.

FIGURE 3. Neostrengeria lassoi n. sp., holotype male, ICN-MHN-CR 3174. A, dorsal view of carapace; B, ventral view of carapace.

FIGURE 4. Neostrengeria lassoi n. sp., holotype male, ICN-MHN-CR 3174. A, left first gonopod, caudal view; B, same, lateral view; C, same, cephalic view; D, same, mesio-caudal view; E, same, detail of apex, distal view; F, left third maxilliped, external view.