Gordonopsis hera, 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 : 285-292

Gordonopsis hera , new species

( Figs. 17–20 )

Material examined. Holotype: ovigerous female (21.8 × 31.2 mm) (MNHN-IU-2013-2245), station CP 4246, northwest of Vitu Island, Bismarck Sea , 04°07′S, 148°09′E, Papua New Guinea, 695–899 m, coll. MADEEP Expedition, 22 April 2014.

Diagnosis. Female: carapace longitudinally pyriform, width to length ratio 0.70, distinctly wider posteriorly than anteriorly; dorsal carapace surface with well-defined regions, separated by broad, deep grooves; lateral margin gently convex to almost straight; dorsal parts with numerous stiff setae that do not obscure surface; lateral parts with denser soft and stiff setae that partially obscure surface, denser on hepatic, pterygostomial and suborbital regions ( Figs. 17 A–C, 18A, B). Rostrum long, sharp, with 2 relatively short, obliquely directed pseudorostral spines, just shorter than rostrum ( Fig. 17B ). Supraorbital margin relatively wide; pseudorostral spines directed obliquely laterally at angle of about 30° ( Fig. 17B ). Eyes with short ocular peduncle, cornea prominent; no discernible orbit ( Fig. 17B ). Hepatic region gently inflated, with short obliquely directed spine ( Fig. 17B ). Gastric region without spines ( Fig. 17B ). Gastric groove well marked, with distinct ovate gastric fossae just above ( Fig. 17B ). Cardiac region swollen; branchial region inflated, with distinct branchio-cardiac grooves ( Fig. 17B ). Latero-posterior tubercle on carapace low, just discernible as granule ( Fig. 17B ). Base of antenna with short spine ( Fig. 18D ). Antennal flagellum short, second and third articles thick, setose. Epistome triangular ( Fig. 18D ). Third maxilliped pediform, merus elongate with dentiform external angle ( Fig. 18C ). Chelipeds long; fingers long, greater than half length of palm; surface gently rugose with scattered small granules; carpus longitudinally ovate, outer margin with 3 or 4 long spines, distal edge with 1 long spine, inner margin with 1 long spine, dorsal surface with longitudinal row of 3 spines; merus triangular in cross-section, relatively long, curved, dorsal margin with 8 spines and distal 2 spines bracketing chela, outer ventral margin with 6 spines, inner ventral margin with 4 or 5 spinules ( Fig. 18 E–I). Ambulatory legs very long; basis-ischium with 4 spines on each margin; P2 merus with 3 spines on dorsal margin (excluding 1 distal spine), ventral margin with 1 spine; P3 merus with 2 spines on dorsal margin (excluding 1 distal spine), ventral margin unarmed; P4 merus with 1 spine on dorsal margin (excluding 1 distal spine), ventral margin unarmed, outer surface smooth, without trace of spinule or granule ( Figs. 17A , 19 D–F). 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 7 spines, that of dactylus with 7 spines ( Fig. 19A, G, H ). Outer margin of P2 coxa with l short, stout spine on distal edge; outer margin of P3 coxa with 1 short, stout spine on proximal edge, outer margin of P4 coxa with 0 or 1 short, stout spine on proximal edge ( Fig. 18J, K ). Proximal part of telson subtruncate, with distal half triangular ( Fig. 19B ). Variation. The photographs from the Tokelau Seamount ( Fig. 20 ) appear to show large specimens of G. hera , which agree very well with the holotype female, including in the pereiopod proportions and armature.

Colour. In life, the carapace is whitish to brown; with the ambulatory legs clear or pale orange with white spines ( Figs. 20 , 30A ).

Etymology. Hera is a Greek goddess, sister and wife of Zeus who was educated by Okeanos and Tethys; she was the one who placed Karkinos in the stars forming the constellation Cancer. It alludes to, and honours, our friend and respected colleague, Danièle Guinot, for her stellar work on marine Brachyura over the years. The name is used as a noun.

Remarks. Specimens were observed by a submersible, in March 2017, at Ufiata Seamount in the Tokelau Seamounts in the central Pacific (8°09.50′S, 172°54.08′W), at depths of 755–995 m ( Fig. 20 ). Although no specimens were collected, the photographs agree very well with what is here described for G. hera and we believe they are conspecific. These seamounts are some 4,000 km east of the type locality of G. hera in the Bismarck Sea.

See general discussion for comparisons with congeners.

Carrying behaviour. The specimens from the Tokelau Seamounts in the central Pacific were all observed carrying an unidentified hydroid colony ( Fig. 20 ). This is the first record of carrying behaviour in this genus (see Guinot et al., 1995; Guinot & Wicksten, 2015).

Figures

Fig. 17. Gordonopsis hera, new species, holotype ovigerous female (21.8 × 31.2 mm) (MNHN-IU-2013-2245), Papua New Guinea. A, overall habitus; B, dorsal view of carapace; C, dorso-frontal view of carapace.

Fig. 18. Gordonopsis hera, new species, holotype ovigerous female (21.8 × 31.2 mm) (MNHN-IU-2013-2245), Papua New Guinea. 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, dorsal view of carpus of left cheliped (denuded); F, dorsal view of carpus of right cheliped (denuded); G, outer view of right chela; H, inner view of right chela; I, dorsal view of right cheliped; J, right P2–P4 coxae and basis-ischia (denuded); K, left P2–P4 coxae (denuded).

Fig. 19. Gordonopsis hera, new species, holotype ovigerous female (21.8 × 31.2 mm) (MNHN-IU-2013-2245), Papua New Guinea. A, dorsal view of carapace showing relative P5 length; B, ventral view of cephalothorax showing pleon; C, telson and pleon somites 5 and 6; D–G, right P2–P5, respectively (all to same scale); H, right P5 pseudochela.

Fig. 20. Gordonopsis hera, new species, photographed in situ, specimens not collected. Ufiata Seamount, Tokelau Seamounts, 8°09.50′S, 172°54.08′W, 755–995 m, March 2017. Photographs courtesy of the U.S. National Oceanographic and Atmospheric Administration Office of Ocean Exploration and Research.

Fig. 30. Colour in life. A, Gordonopsis hera, new species, holotype ovigerous female (21.8 × 31.2 mm) (MNHN-IU-2013-2245), Papua New Guinea; B, G. ceto, new species, holotype female (9.3 × 13.6 mm) (NTOU), South China Sea; C, G. velutina, new species, holotype female (20.8 × 27.8 mm) (MNHN-IU-2013-2269), Admiralty Islands. Photographs: A, C, Laure Corbari (MNHN); B, Chan Tin-Yam (NTOU).