Neostrengeria alexae, Campos, Martha R., 2010

Campos, Martha R., 2010, A new species of freshwater crab of the genus Neostrengeria Pretzmann, 1965, from Colombia (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 2482, pp. 64-68 : 65-67

Neostrengeria alexae new species

Figs. 1 , 2

Holotype. Municipio Medina, Vereda La Zarza, La Cascada stream, elevation 490 m, Cundinamarca Department, Colombia, 4º 27’ 12.5” N - 73º 17.5’ 7.4” W, 29 May 2009, leg. M. R. Campos, 1 male, cl 18.2 mm, cb 31.8 mm, ICN-MHN-CR 2568.

Paratypes. Same locality data as holotype, 5 males, the largest cl 18.7 mm, cb 32.7 mm, the smallest cl 11.4 mm, cb 13.4 mm, 2 females cl 18.8 and 17.1 mm, cb 31.0 and 29.0 mm, CN-MHN-CR 2569.

Diagnosis. First male gonopod straight, wider in the middle; mesial side nearly straight with rounded bulge subdistally; lateral lobe widely semicircular with distal portion rounded, attached to gonopod almost throughout its entire length in caudal view; accessory lobe spatulate with distal portion rounded, distinctly shorter than lateral lobe; distal portion of accessory and lateral lobes separated by wide notch; apex outline oval, caudo-cephalic border broadly rounded, border fringed with sub-acute spines; cephalic spine prominent, sub-acute; mesial lobe subtriangular in apical view, broadly triangular and prominent in mesial view. Exognath of third maxilliped between 0.63 and 0.73 times the length of ischium of endognath.

Description of the holotype. Carapace ( Fig. 1 A) with cervical groove straight, narrow, shallow anteriorly, deep, wide posteriorly, ending some distance from lateral margin; anterolateral margin with shallow sinus just posterior to antero-external orbital angle, with 7 papillae anterior of cervical groove, lateral margin with approximately 20 blunt teeth; posterior margin smooth; postfrontal lobes small, rounded, delimited anteriorly by 2 depression; median groove shallow; front with upper border subtly demarcated by row of tubercles, concave in dorsal view, surface of front between upper, lower borders wide, vertical lower border strongly sinuous in frontal view, fringed with tubercles, protruding more than upper border in dorsal view; orbital margins each with row of rounded tubercles ( Fig. 1 B); dorsal surface of carapace smooth, covered by small papillae, regions distinctly marked; third maxilliped with merus having rounded angle on distal half of external margin, exognath 0.73 times length of ischium ( Fig.1 D); efferent branchial channel open, rectangular ( Fig. 1 E).

First pereopods heterochelous ( Fig. 1 A, C); left cheliped larger than right; merus with 3 crests: upper crest with rows of low blunt tubercles, internal lower crest with row of 10 blunt teeth, increasing in size distally, external lower crest with row of low blunt tubercles; carpus with 3 tubercles, distal prominent blunt spine; palms of both chelipeds smooth, swollen; fingers of chelae not gaping when closed, tips crossing, outer, inner surfaces with rows of small tubercles. Walking legs (second to fifth pereopods) slender, dactyli each about 1.4 times as long as propodi, with papillae, 5 longitudinal rows of large spines diminishing in size proximally. Spines, papillae on each dactylus arranged as follows: 1 antero-lateral row, 1 antero-ventral row each with 5 spines; 1 external row with 5 spines, 2 intercalated papillae, 2 proximal papillae; 1 postero-ventral row, 1 postero-lateral row each with 4 spines.

First male gonopod straight, wider in the middle; mesial side nearly straight with subdistal rounded bulge; caudal margin nearly straight, fringed with spines distally, with conspicuous setae proximally; lateral lobe widely semicircular with distal portion rounded, attached to gonopod almost throughout its entire length in caudal view; accessory lobe spatulate with distal portion rounded, directed laterally, distinctly shorter than lateral lobe ( Fig. 2 A), distal portion of accessory, lateral lobes separated by wide notch in lateral view ( Fig. 2 C); apex outline oval in distal view, caudo-cephalic border broadly rounded, border fringed with sub-acute spines; cephalic spine prominent, sub-acute ( Fig. 2 E); mesial lobe subtriangular in apical view, broadly triangular, prominent in mesial view, cephalically directed ( Fig. 2 B); mesocaudal projection of spermatic channel bifid at distal end, exposed side narrow with acute papilla, internal side wide with rounded papilla; surface of apex covered by rows of conspicuous spines ( Fig. 2 E)

Color. The alcohol-preserved holotype is brown (near Burnt Umber, 22 [ Smithe (1975]) on the dorsal side of the carapace. The walking legs are mottled brown (near Raw Umber, 23) dorsally and light brown (near Clay Color, 26) ventrally. The chelae are brown (Raw Sienna, 136) dorsally and light brown (True Cinnamon, 139) ventrally. The ventral surface of the carapace is light brown (near Cinnamon, 39).

Habitat. The specimens were collected under rocks in a clear mountain stream with a gravel and sand bottom. The stream bed had a slope of 30 to 40 degrees, and the current was very strong.

Etymology. The species is dedicated to the young Colombian-American naturalist Alexandra Campos.

Remarks. Neostrengeria alexae n. sp. can be distinguished from the other species of the genus by (a) the shape of the accessory lobe, which is spatulate and rounded distally, (b) the outline of the apex, which is oval with the caudo-cephalic border broadly rounded and the entire border fringed with sub-acute spines. The lateral lobe of the new species is semicircular and differs from the elongated or rounded lobe of the following species: N. appressa Campos, 1992 , N. aspera Campos, 1992 , N. bataensis Campos & Pedraza, 2008 , N. boyacensis Rodríguez, 1980 , N. celioi Campos & Pedraza, 2008 , N. charalensis Campos & Rodríguez, 1985 , N. gilberti Campos, 1992 , N. guenteri ( Pretzman, 1965) , N. libradensis Rodríguez, 1980 , N. lobulata Campos, 1992 , N. macarenae Campos, 1992 , N. macropa (H. Milne Edwards, 1853) , N. niceforoi ( Schmitt, 1969) , N. perijaensis Campos & Lemaitre, 1998 , N. tencalanensis Campos, 1992 and N. tonensis Campos, 1992 . N. alexae n. sp. slightly resembles N. sketi Rodríguez, 1985 in the shape of the lateral lobe, but in the new species the lateral lobe is attached to the gonopod almost throughout its entire length in caudal view, whereas in N. sketi it is separated from the gonopod on the distal half. The mesial lobe is developed into either a rounded or elongated projection, or is reduced to a strong fold in the following species: N. aspera Campos, 1992 , N. gilberti Campos, 1992 , N. lobulata Campos, 1992 , N. macarenae Campos, 1992 , N. perijaensis Campos & Lemaitre, 1998 , N. tencalanensis Campos, 1992 and N. tonensis Campos, 1992 , whereas in the new species the mesial lobe is triangular and prominent.

Figures

FIGURE 1. Neostrengeria alexae new species, holotype male, ICN-MHN-CR 2568. A, habitus; B, frontal view of carapace; C, large cheliped, external view; D, left third maxilliped, external view; E, left efferent branchial channel, external view.

FIGURE 2. Neostrengeria alexae new species, holotype male, ICN-MHN-CR 2568. A, left first gonopod, caudal view; B, same, mesial view; C, same, lateral view; D, same, cephalic view; E, same, apex distal view. 1, lateral lobe; 2, accessory lobe; 3, mesial lobe; 4, cephalic spine; 5, meso-caudal projection of spermatic channel.