Gordonopsis robusta Ng, Padate & Saravanane, 2019

Ng, Peter K. L. & Forges, Bertrand Richer de, 2020, A revision of the deep-sea porter crabs of the genus Gordonopsis Guinot & Richer de Forges, 1995 (Crustacea, Decapoda, Brachyura, Homolidae), with descriptions of five new species, Raffles Bulletin of Zoology 68, pp. 267-307 : 278-284

Gordonopsis robusta Ng, Padate & Saravanane, 2019

( Figs. 12 , 13 )

Gordonopsis robusta Ng, Padate & Saravanane, 2019: 511 , figs. 1–4.

Material examined. Holotype: male (33.5 × 44.9 mm) (CMLRE IO/SS/BRC/00082), Andaman Sea, FORVSS station 36708, 13.27°N, 93.26°E, 635 m, HSDT (CV), coll. S. S. Cubelio, 26 November 2017. Paratype: 1 young female (15.6 × 20.8 mm) (CMLRE IO/SS/BRC/00083), same data as holotype.

Diagnosis. Male: carapace longitudinally ovate, width to length ratio 0.75, distinctly wider posteriorly than anteriorly; dorsal carapace surface with well-defined regions, separated by broad, deep grooves; lateral margin distinctly convex; dorsal parts with dense soft setae partially obscuring surface; lateral parts densely setose, completely obscuring surface ( Figs. 12 A–D, 13A, B). Rostrum relatively long, sharp, with 2 relatively long, obliquely directed pseudorostral spines, just shorter than rostrum ( Fig. 12C ). Supraorbital margin relatively narrow, C-shaped; pseudorostral spines directed obliquely laterally at angle of about 45° ( Fig. 12C ). Supraorbital margin relatively narrow, C-shaped; pseudorostral spines directed obliquely laterally at angle of about 45° ( Fig. 12C ). Eyes with short ocular peduncle, cornea prominent; no discernible orbit ( Fig. 12C ). Hepatic region gently inflated, with short obliquely directed spine ( Fig. 12C ). Gastric region without spines ( Fig. 12C ). Gastric groove well marked, with distinct ovate gastric fossae just above ( Fig. 12C ). Cardiac region swollen; branchial region inflated, with distinct branchio-cardiac grooves ( Fig. 12C ). Latero-posterior tubercle strong, sharp ( Fig. 12C ). Base of antenna with short spine. Antennal flagellum short, second and third articles thick, setose. Epistome triangular. Third maxilliped pediform, merus elongate with dentiform external angle ( Fig. 13C ). Chelipeds long; fingers short, less than half length of palm; surface gently rugose with 4 or 5 longitudinal rows of small granules, margins with sharp granules and short spines; carpus longitudinally ovate, outer margin with 8–10 short spines, distal edge with short spine, inner margin with 5 or 6 spines, dorsal surface with ridge lined with 3–5 short sharp tubercles or granules; merus triangular in cross-section, relatively long, curved, dorsal margin with 5 short spines and distal 2 spines bracketing chela, outer ventral margin with 16–18 spines and spinules, inner ventral margin with 6–8 spines or spinules ( Figs. 12A, E , 13F ). Ambulatory legs relatively long; basis-ischium with small granules, not spines; P2 merus with 6 spines or sharp tubercles on dorsal margin (excluding 1 distal spine), ventral margin with 3–5 spinules or tubercles; P3 merus with 5 spines on dorsal margin (excluding 1 distal spine), ventral margin with 1 or 2 sharp tubercles; P4 merus not known ( Figs. 12A, B , 13G, H ). P5 merus slender, unarmed on all margins, just reaching gastric groove when folded anteriorly; carpus long, propodus short, enlarged, forming prominent pseudochela with stout, gently curved dactylus; occlusal margin of fixed finger with 8 spines, that of dactylus with 8 spines ( Figs. 12D , 13I, J ). Outer margins of P2–P4 coxae smooth, unarmed ( Fig. 13D, E ). Telson triangular, with gently convex lateral margins and sharp tip ( Fig. 13D, E ). G1 short, stout, distal part gently upcurved, tip concave ( Fig. 13K ). G2 stout, tubular, length subequal to G1, distal portion cup-shaped ( Fig. 13L ). Female: non-sexual characters similar to male except cheliped merus with 6 spines on upper margin, 8 short spines and tubercles on outer ventral margin, 5 or 6 sharp tubercles on inner ventral margin; P2 merus with 5 spines on dorsal margin, ventral margin with 1 sharp tubercle; P3 merus with 5 spines on dorsal margin, ventral margin with 1 sharp tubercle; P4 with 3 spines on dorsal margin, ventral margin unarmed; telson broadly triangular with convex lateral margins.

Colour. Not known.

Remarks. See general discussion for comparisons with congeners.

Figures

Fig. 12. Gordonopsis robusta Ng, Padate & Saravanane, 2019. A, C, E, holotype male (33.5 × 44.9 mm) (CMLRE), Andaman Sea; B, D, paratype female (15.6 × 20.8 mm) (CMLRE), Andaman Sea. A, B, overall habitus; C, dorsal view of carapace; D, dorsal view of carapace showing relative P5 length; E, outer view of right chela.

Fig. 13. Gordonopsis robusta Ng, Padate & Saravanane, 2019, holotype male (33.5 × 44.9 mm) (CMLRE), Andaman Sea. A, dorso-lateral view of cephalothorax; B, frontal view of cephalothorax; C, right third maxilliped; D, E, ventral view of cephalothorax showing pleon and coxae; F, dorsal view of carpus of right cheliped; G–I, left P3–P5 meri and leg, respectively (all to same scale); J, left P5 pseudochela; K, ventral view of right G1; L, ventral view of right G2.