Phallangothelphusa martensis, Cardona, Luisa & Campos, Martha R., 2012

Cardona, Luisa & Campos, Martha R., 2012, A new species of freshwater crab of the genus Phallangothelphusa Pretzmann, 1965, from Colombia (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 3515, pp. 83-88 : 84-88

Phallangothelphusa martensis , new species

( Figs. 1‒3 )

Holotype. Municipio San Martín, Vereda La Unión, La Batea Stream, elevation 290 m, Cesar Department, Colombia, 7° 59´42.4ʺ N, 73° 24´20.9ʺ W, 3 Nov. 2011, leg. L. Cardona, 1 male, cl 17.3 mm, cb 30.1mm, ICN- MHN-CR 2656.

Paratypes. Same locality data as holotype, 2 males, cl 16.5 and 15.1 mm, cb 28.4 and 25.5 mm, 5 juveniles, cl 7.8–10.1 mm, cb 12.9–16.7 mm, ICN-MHN-CR 2666.

Additional material examined: Municipio San Martín, Vereda Alto de la Raya, stream by Rosmira Farm, elevation 320 m, César Department, Colombia, 8° 4´7.2ʺ N, 73° 25´8.06ʺ W, 26 Aug. 2011, leg. L. Cardona, 1 male, cl 15.5 mm, cb 26.3 mm, ICN-MHN-CR 2654.— Municipio San Martín, Vereda Alto de la Raya, La Raya Stream, elevation 290 m, César Department, Colombia, 8° 3´8ʺ N, 73° 25´9ʺ W, 10 Mar 2007, leg. Y. Muñoz, 1 male, cl 15.0 mm, cb 26.2 mm, ICN-MHN-CR 2443.

Diagnosis. Third maxilliped with exognath 0.9 times length of ischium. Lateral side of first male gonopod with subdistal constriction, prominent ridge running parallel to caudal lobe; mesial process formed by 2 projections: distal, proximal, curvature between them greater than 90°, distal projection triangular in caudal view, with basal acute spine, directed downwards in distal view; proximal projection rectangular with notch on basal portion; lateral process nearly semicircular, inwardly turned, parallel to axis of gonopod (60%), remaining 40% projected mesially; apex outline oval in distal view.

Description of the holotype. Carapace ( Fig. 1 A) with straight, wide, deep cervical grooves, becoming indistinct towards margins of carapace; antero-lateral margins with wide deep notch behind outer orbital angle, notch fringed by papillae, with 5 papillae before cervical grooves; lateral margins with approximately 14 papilliform teeth, diminishing in size posteriorly; postfrontal lobes high, oval, delimited anteriorly by transverse depression; median groove shallow; front high, slightly excavated, upper border convex with slight middle depression in dorsal view, marked with row of papillae, lower margin sinuous in frontal view, conspicuously thickened; upper, lower orbital margins each fringed with tubercles ( Fig. 1 B); dorsal surface of carapace smooth, covered by small papillae, regions demarcated; third maxilliped with shallow depression on subdistal external margin of merus, exognath 0.9 times length of ischium ( Fig. 1 E); orifice of efferent branchial channel open, nearly ovate with recurved extension of lateral lobe of epistome ( Fig. 1 C).

First pereopods heterochelous ( Fig. 1 A); right cheliped larger than left; merus with 3 crests as follows: upper crest with rows of tubercles of different sizes, internal lower crest with 2 tight rows of tubercles, diminishing in size proximally, external lower crest with row of papillae; carpus with blunt subdistal spine, follows by 6 rounded tubercles, decreasing in size proximally; palms of both chelipeds smooth, swollen, with row of papillae on external, internal margin; fingers of chelae with rows of tubercles, gaping when closed, tips crossing ( Fig. 1 D). Walking legs (second to fifth pereopods) slender ( Fig. 1 A), dactyli each about 1.5 times as long as propodi, with 5 longitudinal rows of large spines diminishing in size proximally, arrangement of spines on dactylus of left second pereopod as follows: anterolateral, anteroventral rows each with 8 spines, external row with 9 spines, postero-ventral, posterolateral rows each with 4 spines.

First male gonopod with subdistal portion bent laterally; caudal lobe wide basally, distally, narrower near middle, hourglass-like, subdistal portion bent laterally, in caudal view; lateral side with subdistal constriction, prominent ridge running parallel to caudal lobe; mesial process formed by 2 projections (distal, proximal), separated by wide curvature between; distal projection triangular, semi-acute distally, in caudal view, with basal acute spine, directed downwards in distal view; proximal projection rectangular, recurved meso-caudally with notch on basal portion in caudal view ( Figs. 2 A, D, E); lateral process near semicircular, inwardly turned, parallel to axis of gonopod, approximately 60% of length, remaining 40% projected mesially, basal portion covered by rows of spinules, separated from proximal projection of mesial process by deep gap ( Fig. 2 C–E); lateral process as long as proximal projection of mesial process; apex outline oval in distal view ( Fig. 2 D, E); conspicuous caudal setae basally, laterally. Second male gonopod slightly sinuous with distal internal portion nearly flat, covered by rows of spinules ( Figs. 2 F, G).

Color. The freshly‒alcohol‒preserved holotype is brown (near Burn Umber, 22) with light specks (near Cinnamon, 123A) on the posterior dorsal side of the carapace. The walking legs dorsally, ventrally brown (Burn Umber, 22). The chelae brown dorsally (near Mikado Brown, 121C), light brown ventrally (near Sayal Brown, 223C). The ventral surface of the carapace is brown (near Olive Brown, 28) with light specks (near Sayal Brown, 223C) posteriorly.

Habitat. The specimens were collected by hand, under not submerged rocks in secondary forest streams (2 m average width, depth between 30 cm and 1.50 m). The streams were surrounded by a gallery forest and were characterized by low turbidity water, sandy clay soil and pebble substrate.

Etymology. The species is named after the type locality, Municipio San Martín, Colombia.

Remarks. This new species closely resembles Phallangothelphusa dispar (Zimmer, 1912) (see Campos 2005: figs. 40A–H). The main distinguishing feature between the two species is the first male gonopod. The gonopod of P. martensis has a laterally bent subdistal portion (straight in P. d i s p a r); the caudal lobe is hourglass-like, narrower near the middle portion, with subdistal portion laterally bent (straight, with slight subdistal constriction in P. dispar ); the lateral side has a subdistal constriction and a prominent ridge running parallel to the caudal lobe (only a subdistal slight depression in P. dispar ); the curvature between the distal and proximal projections of the mesial process in greater than 90° ( Fig. 3 A) (nearly 60° in P. dispar ; Fig. 3 B); the inner margin of the curvature slightly overlaps the mesial surface ( Fig. 3 A) (extensively overlaps the mesial surface, ending in a wide base spine in P. dispar ; Fig. 3 B); the distal projection is triangular, semi-acute distally, in caudal view, with a basal acute spine directed downwards, in distal view ( Fig. 3 A) (rounded and devoid of the basal spine in P. d i s p a r; Fig. 3 B); the proximal projection has a notch on basal portion in caudal view ( Fig. 3 A) (a slight depression in P. dispar ; Fig. 3 B); the lateral process is inwardly turned and parallel to the axis of the gonopod, approximately 60% of the length, the remaining 40% projected mesially ( Fig. 3 A) (perpendicular to the axis of gonopod and projected mesially, covering the proximal projection of the mesial process in P. dispar ; Fig. 3 B). Another morphological character that can be used to differentiate the two species is the length of the exognath of the third maxilliped, which corresponds to 0.9 times the length of the ischium in P. martensis ( Fig. 1 E), whereas it is only 0.8 times in P. dispar ( Campos 2005: fig. 40 E).

In some of the specimens examined the length of the lateral process was shorter than the proximal projection of the mesial process and the gap between them was minor.

Figures

FIGURE 1. Phallangothelphusa martensis new species, male holotype, 1 male, cl 17.3 mm, cb 30.1 mm, ICN-MHN-CR 2656. A, habitus; B, frontal view of carapace; C, opening of left efferent branchial channel, external view; D, chela of large cheliped, external view; E, left third maxilliped, external view.

FIGURE 2. Phallangothelphusa martensis new species, male holotype, ICN-MHN-CR 2656. A, left first gonopod, caudal view; B, same, lateral view; C, same, mesial view; D, same, cephalic view; E, apex distal view; F, second gonopod, caudal view; G, distal part of second gonopod. 1, distal projection of mesial process; 2, curvature; 3, proximal projection of mesial process; 4, lateral process.

FIGURE 3. Phallangothelphusa martensis new species, male holotype, ICN-MHN-CR 2656, left first gonopod: A, apex distal view; Phallangothelphusa dispar (Zimmer, 1912), ICN-MHN-CR 0 732, left first gonopod: B, apex, distal view. 1, distal projection of mesial process; 2, curvature; 3, proximal projection of mesial process; 4, lateral process.