Colombiathelphusa culmarcuata, Campos, Martha R. & Magalhães, Célio, 2014

Campos, Martha R. & Magalhães, Célio, 2014, Colombiathelphusa, a new genus of freshwater crab from Colombia, and the first location record of Eidocamptophallus chacei (Pretzmann, 1967) (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 3860 (6), pp. 571-579 : 572-576

Colombiathelphusa culmarcuata n. sp.

Figs. 1 , 2

Holotype. Male, cl 25.6 mm, cb 43.2 mm (ICN-MHN-CR 2801); Municipio Unguía, Corregimiento Gilgal, stream in Peñitas Farm, Chocó Department, Colombia, elevation 112 m, 08º11’47.83” N 77º06’33.28” W, 18 Apr 2014, leg. G. F. Medina.

Paratypes. Female, cl 25.0 mm, cb 37.3 mm, 2 juvenile males, cl 14.0 and 12.9 mm, cb 19.8 and 18.6 mm (ICN-MHN-CR 2802); Municipio Unguía, Corregimiento Gilgal, stream in Peñitas Farm, Chocó Department, Colombia, elevation 105 m, 08º11’47.0” N 77º06’39.54” W, 19 Apr 2014, leg. G. F. Medina.

Additional voucher material. Male, cl 16.4 mm, cb 25.0 mm (ICN-MHN-CR 2745); Municipio Unguía, Corregimiento Titumate, stream by Darío Márquez Farm, Chocó Department, Colombia, elevation 179 m, 08º16’38.24” N 77º04’33.13” W, 20 Sep 2013, leg. G. F. Medina.— Two females, cl 15.1 and 11.7 mm, cb 22.5 and 17.9 mm (ICN-MHN-CR 2747); Municipio Unguía, Corregimiento Titumate, stream in Reserva Natural Ormuz, Chocó Department, Colombia, elevation 125 m, 08º16’1.71” N 77º05’37.96” W, 15 Sep 2013, leg. G. F. Medina.— Juvenile male, cl 12.7 mm, cb 19.3 mm (ICN-MHN-CR 2746); Municipio Unguía, Corregimiento Gilgal, stream by Reserva Natural La Tribu, Chocó Department, Colombia, elevation 106 m, 08º11’46.86” N 77º06 38.45” W, 20 Sep 2013, leg. G. F. Medina.

Additional material examined. Ptychophallus goldmanii Pretzmann, 1965 , male, cl 17.3 mm, cb 26.4 mm, holotype, USNM 54044, Panamá, Darién Province, Mount Cana, 07°48’N 77°32’W, Cana, 24.v.1912, leg. E.A. Goldmann.

Diagnosis. See diagnosis of the genus.

Description of the holotype. Carapace ( Fig. 1 A) with straight, narrow cervical groove, ending far from lateral margin; anterolateral margin with deep sinus just posterior to antero-external orbital angle, with 5 papillae anterior of cervical groove, lateral margin with approximately 12 blunt teeth; posterior margin smooth; postfrontal lobes low, oval, delimited anteriorly by 2 depressions; median groove shallow, with incision on upper border of front; front with upper border demarcated by row of tubercles, slightly concave in dorsal view, surface of front between upper, lower borders wide, excavated, lower border nearly straight 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 external margin of merus regularly rounded, exognath 0.60 times length of ischium ( Fig. 1 C); efferent branchial channel open, nearly subquadrate ( Fig. 1 D).

First pereopods heterochelous ( Fig. 1 A, C); right cheliped larger than left; merus with 3 crests: upper crest with rows of blunt tubercles, internal lower crest with row of 10 blunt teeth, increasing in size distally, external lower crest with row of blunt tubercles; carpus with 4 blunt spines, distal prominent, acute spine; palms of both chelipeds smooth, swollen, dorsal surface covered by rows of low tubercles; fingers of larger chela gaping when closed, fingers of smaller one not gaping when closed, outer, inner surfaces with rows of small tubercles, fingers of both chelae with large triangular teeth. Walking legs (second to fifth pereopods) slender, dactyli each about 1.6 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, antero-ventral row each with 5 spines, proximal papilla; external row with 5 spines, 2 proximal papillae; postero-ventral row, postero-lateral row each with 3 spines.

Male first gonopod straight, wider in mid-distal portion, slightly recurved distally towards cephalic side in mesial, lateral views; mesial side with marginal suture nearly straight along most of the stem, proximal portion forming slightly rounded lobe with conspicuous long setae, ending as reduced, acute marginal process; spine-like mesial process partially displaced towards cephalic side, pointing in mesocephalic direction, directed proximally; mesial border with irregular rows of short translucent setae; lateral side almost straight, slightly bend towards cephalic side distally, with some short setae, proximal portion slightly sinuous, distinct middle constriction, lateral process well developed, rounded, extending from middle to subdistal portion, followed by deep subdistal incision; caudal side with longitudinal, nearly straight, proximal ridge, ending in narrow ridge distally, strongly swollen subdistally, distal border broadly rounded in distocephalic view, with subtriangular projection to lateral side in caudal view; distal portion of cephalic side strongly concave transversally, with 2 subdistal spine-like processes, cephalic border distinctly curved; apex outline elongated, strongly recurved in crosswise direction like a bow's arch, both caudal, cephalic borders thick, lateral ends bifid, with internal acute spine (cephalic side), external blunt spine (caudal side) in distal, apical views; field of apical spines in distal position, poorly developed, rather elongated, with short spines; spermatic channel with rows of conspicuous spinules.

Color. The alcohol-preserved holotype is mottled gray (near Grayish Horn Color, 91; Smithe 1975) on the dorsal side of the carapace. The walking legs are greenish-grey (near Grayish Horn Color, 91) dorsally, light gray (near Drab-Gray, 119D) ventrally. The chelae are gray (near Drab Gray, 119D) dorsally, light gray (near Light Drab, 119C) ventrally. The ventral surface of the carapace is yellow-brown (near Buff, 124).

Habitat. The specimens were collected in a stream of clear water, rocky substrate, one meter wide and an average depth of 30 cm. The stream is in the middle of a well-structured forest, with coverage of 80% and high vegetation covering the edges of the stream.

Etymology. The specific name is derived from the Latin culmen for “crown,” and arcuatus, meaning shaped like a bow's arch, and in reference to the recurved form of the apex of the male first gonopod.

Remarks. The first male gonopod of Colombiathelphusa culmarcuata n. sp. has some peculiar features such as a reduced, acute marginal process, a spine-like mesial process partially displaced towards the cephalic side, two subdistal spine-like cephalic processes, and a bifid lateral end of the apex. These features suggest that the species followed a rather distinct evolutionary lineage among the Hypolobocerini that has led us to erect a new genus to accommodate it. C. culmarcuata n. sp. seems to be more closely related to Ptychophallus goldmanni Pretzmann, 1965 , because of some similarities in the lateral process (well developed, but reduced to a distal segment), the marginal process (reduced in both, but acute in the new species and rounded in P. goldmanni ), and in the divided lateral end of the apex (symmetrically bifid, with cephalic end acute in the new species, asymmetrically bifid, with cephalic end larger and rounded in P. goldmanni ). These affinities might also be better understood because their geographical ranges are close but separated by a mountain range: C. cumarcuata n. sp. occurs on the eastern slope of the southern portion of the Serranía de Darién in the Department of Chocó, Colombia, whereas P. goldmanni is found on the western slope of this mountain range in the Province of Darién, Panamá (see Rodríguez 1994), at approximately the same latitude (approximately 8° N).

Rodríguez & Hedström (2000) commented on the situation of the lateral lobe in relation to the components of the apex, which form a structure that would serve to retain the spermatophore in the gonopods of Ptychophallus . In P. goldmanni the lateral process and the cephalic border of the strongly bent apex form an almost closed, channellike receptacle, transversal to the main axis of the stem (see Rodríguez & Hedström 2000: 424, fig. 2E). In C. culmarcuata n. sp. the apex is not markedly bent towards the cephalic side, but its strong transverse curvature in conjunction with its sharp lateral edge and the cephalic spine-like processes seems to form a longitudinal receptacle for the spermatophore.

Besides the characters that are diagnostic for the tribe, further similarities between the gonopod of C. culmarcuata n. sp. and the other species of Hypolobocera , Moritschus , and Lindacatalina are not discernible. These genera are widely distributed in Colombia, but their species are more common in the south ( Campos 2005), and also in Ecuador ( Rodríguez & Sternberg 1998) and Peru ( Rodríguez & Suárez 2004). Even the few species that are geographically closer, such as Hypolobocera murindensis Campos, 2003 (from Murindó, Antioquia Department, Atrato River basin) and Lindacatalina sinuenis Rodríguez, Campos & López, 2002 (from Cordoba Department, Sinú River basin), have gonopods with a very distinct morphology (see descriptions and illustrations in Campos 2005).

Figures

FIGURE 1. Colombiathelphusa culmarcuata n. sp., holotype male, ICN-MHN-CR 2801. A, habitus; B, frontal view of carapace; C, left third maxilliped, external view; D, left efferent branchial channel, external view.

FIGURE 2. Colombiathelphusa culmarcuata n. sp., holotype male, ICN-MHN-CR 2801. A, left first gonopod, caudal view; B, same, cephalic view; C, same, lateral view; D, same, mesial view; E, same, detail of apex, disto-cephalic view; F, apex, distal view. 1, marginal suture; 2, marginal process; 3, lateral projection; 4, lateral process: 5, caudal ridge; 6, mesial process; 7, cephalic processes; 8, internal spine of apex; 9, external spine of apex.