Gordonopsis alaini, Ng & Forges, 2020

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

Gordonopsis alaini , new species

( Figs. 9–11 )

Paromola profundorum – Guinot & Richer de Forges, 1981: 536,

figs. 3A, 4F, 5A, A1, pl. 3 fig. 1, 1a. Gordonopsis aff. profundorum – Guinot & Richer de Forges, 1995:

467, figs. 63d–h, 64A, B. Gordonopsis profundorum – Garassino, 2009: 11, pl. 2.

Material examined. Holotype: male (10.9 × 16.8 mm) (MNHN-IU-2017-9049 = MNHN B-7026), station CH38 P3 trawl 38, 12°50.0′S, 48°09.1′E, northwest coast, Madagascar, 580–585 m, coll. CREVETTIERE 1972, A. Crosnier, 14 September 1972.

Diagnosis. Male: carapace longitudinally pyriform, width to length ratio 0.65, distinctly wider posteriorly than anteriorly; dorsal carapace surface with well-defined regions, separated by broad, deep grooves; lateral margin sinuous, almost straight; dorsal parts with scattered soft setae, not obscuring surface; lateral parts more setose but not obscuring surface ( Figs. 9 A–C, 10A, B). Rostrum relatively long, sharp, with 2 long, obliquely directed pseudorostral spines, just shorter than rostrum ( Fig. 9B ). Supraorbital margin relatively narrow, C-shaped; pseudorostral spines directed obliquely laterally at angle of about 45° ( Fig. 9B ). Eyes with short ocular peduncle, cornea prominent; no discernible orbit ( Fig. 9B ). Hepatic region not inflated, with short obliquely directed spine ( Fig. 9B ). Gastric region without spines ( Fig. 9B ). Gastric groove well marked, with distinct ovate gastric fossae just above ( Fig. 9B ). Cardiac region swollen; branchial region inflated, with distinct branchio-cardiac grooves ( Fig. 9B ). Latero-posterior tubercle on carapace very low, barely discernible ( Fig. 9B ). Base of antenna with short spine ( Fig. 10D ). Antennal flagellum short, second and third articles thick, setose. Epistome triangular ( Fig. 10D ). Third maxilliped pediform, merus elongate with spiniform external angle ( Fig. 10C ). Chelipeds long; fingers stouter, about two-thirds length of palm; surface gently rugose to smooth; carpus longitudinally ovate, outer, distal, and inner margins with 1 long spine each, dorsal surface with low ridge but unarmed; merus triangular in cross-section, relatively long, curved, dorsal margin with 7 spines and distal 2 spines bracketing chela, outer ventral margin with 7 spines, inner ventral margin with 6 spinules ( Figs. 9A , 10 E–G). Ambulatory legs relatively long; basisischium with small granules, not spines; P2 merus with 3 spines on dorsal margin (excluding 1 distal spine), ventral margin with 2 spinules; P3 merus with 3 spines on dorsal margin (excluding 1 distal spine), ventral margin unarmed; P4 merus with 2 spines on dorsal margin (excluding 1 distal spine), ventral margin unarmed, outer surface with 1 strong proximal spine ( Figs. 9A , 11A , E–G). P5 merus slender, unarmed on all margins, reaching beyond gastric groove when folded anteriorly; carpus long, propodus short, enlarged, forming prominent pseudochela with stout, gently curved dactylus; occlusal margin of fixed finger with 5 or 6 spines, that of dactylus with 5 or 6 spines ( Fig. 11 H–K). Outer margins of P2–P4 coxae smooth, unarmed ( Fig. 11C ). Telson triangular, with convex lateral margins, distal part distinctly narrowing ( Fig. 11B, D ). G1 short, stout, distal part prominently narrowed with subtruncate tip ( Fig. 10H ). G2 stout, tubular, length subequal to G1, basal portion slightly dilated, covered with long setae, distal portion cup-shaped ( Fig. 10I ).

Colour. Not known.

Etymology. The species is named after our good friend Alain Crosnier, who first collected this species. Alain has changed the face of modern carcinology through his many decades of work, for which we are most grateful.

Remarks. See general discussion for comparisons with congeners.

Figures

Fig. 9. Gordonopsis alaini, new species, holotype male (15.4 × 10.0 mm) (MNHN-IU-2017-9049), Madagascar. A, overall habitus; B, dorsal view of carapace; C, dorso-frontal view of carapace.

Fig. 10. Gordonopsis alaini, new species, holotype male (15.4 × 10.0 mm) (MNHN-IU-2017-9049), Madagascar. A, lateral view of cephalothorax; B, frontal view of cephalothorax; C, left third maxilliped; D, ventral view showing buccal cavity, epistome, antennae, and antennules; E, outer view of right carpus and chela; F, dorsal view of left cheliped; G, dorsal view of right cheliped; H, ventral view of right G1; I, ventral view of right G2.

Fig. 11. Gordonopsis alaini, new species, holotype male (15.4 × 10.0 mm) (MNHN-IU-2017-9049), Madagascar. A, dorsal view of carapace showing relative P5 length; B, ventral view of cephalothorax showing pleon and unarmed P2–P4 coxae; C, ventral view of cephalothorax showing sternopleonal cavity and unarmed P2–P4 coxae; D, pleon; E–H, right P2–P5, respectively (all to same scale); I, right P5 pseudochela (same scale as E–H); J, left P5; K, left P5 pseudochela.