Gordonopsis Guinot & Richer de Forges, 1995

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 : 268

Gordonopsis Guinot & Richer de Forges, 1995

Type species. Homola profundorum Alcock & Anderson, 1899 , by original designation and monotypy.

Diagnosis. Carapace longitudinally ovate to subpyriform, anterior half of carapace narrower than posterior half; dorsal surface not ornamented but with scattered to dense setae; gastric fossa distinct; cervical groove pronounced; homolian line (linea homolica) on each side prominent; subhepatic region gently convex but not swollen, with short spine; rostral spine long, thick, pseudorostral spines well developed, directed anterolaterally; no teeth or latero-anterior spines, gastric and cardiac regions gently convex; latero-posterior edge with low prominence or distinct tooth or spine; orbit absent; ocular peduncle short, stout; infra-orbital spine absent; acute antennal spine, visible dorsally; antennal articles 2 and 3 very wide, with strong external distal spine, article 4 relatively short, broad; proepistome weakly developed; epistome very reduced; third maxilliped pediform, narrow, covering only part of buccal frame, anterior margin of merus exceeding endostomial crest; chelipeds not prominently elongate, fingers relatively long, thin, without pigmented spot at base of pollex; P2–P4 relatively long; merus long, dorsal margins armed with spines, ventral margin with short spines or unarmed; proximal part of outer surface of P4 may have tubercle or short spine on outer surface or unarmed; P5 short, total length less than length of P4 merus; merus slender, unarmed on all surfaces, reaching to gastric groove or mesogastric region on the carapace above gastric fossae, propodus and dactylus subchelate, occluding margins with long spines; male pleon locked between coxae of P1–P4: spinule present on inner margin of each coxa of P1–P3 that locks pleon to appress it to sternum; anterior tip of telson positioned between basis and coxa of third maxillipeds; lock present as “homolid press button” mechanism (sternal prominence on outer edge of sternite 4 above articular condyle of P1 coxa, socket in inner surface of pleonal somite 6); male and female pleon with 6 free somites and telson; G1 stout, short with distal part tapering; G2 short, as long as G1, distal part spatuliform. (Modified from Guinot & Richer de Forges, 1995: 463)

Remarks. Gordonopsis Guinot & Richer de Forges, 1995 , was established for a rare species formerly placed in Paromola Wood-Mason in Wood-Mason & Alcock, 1891 ( Alcock, 1901; Doflein, 1904; Ihle, 1913). Only one species was known at that time, G. profundorum ( Alcock & Anderson, 1899) , described from three young female specimens (ca. 13.0 × 9.0 mm) collected in the western Indian Ocean off the Travancore coast, India (7°17′30″N, 76°54′30″E) at a depth of 796 m ( Alcock & Anderson, 1899: 5; Alcock, 1901: 65) ( Fig. 1 ). The species was subsequently reported from the east coast of Africa by Doflein (1904: 16) from a male 24 mm in carapace length, with Gordon (1950: 220) recording a male 16.0 × 11.0 mm from the Maldives. Guinot & Richer de Forges (1981: 536) later examined a male 15.4 × 10.0 mm from Madagascar.

Guinot & Richer de Forges (1995) studied the material from the Maldives and Madagascar as well as one broken specimen from the Seychelles and observed differences between the description of G. profundorum as described and figured by Alcock & Anderson (1899) and Alcock (1901). As such, they were uncertain if all the specimens were conspecific. The Seychelles specimen was too damaged to be useful. Guinot & Richer de Forges (1995) identified their material as “ Gordonopsis aff. profundorum ”, particularly for the specimen from the Maldives, which according to them, had a more bulging carapace as well the possession of a distinct short spine on the latero-posterior part of the carapace, just behind the branchio-hepatic groove ( Fig. 2B ). The specimen from Madagascar ( Fig. 9B ) agrees with the type description and figures of G. profundorum in possessing a short spine on the latero-posterior part of the carapace ( Fig. 9B ). Alcock & Anderson (1899: 10, pl. 1 fig. 2) noted that there was a “blunt denticle near the middle of the ill-defined lateral border” of the carapace and their figures actually show this ( Fig. 1B ). The excellent figure of the East African specimen by Doflein (1904) also shows a latero-posterior tubercle on the carapace ( Fig. 6B ). The specimen from the Maldives has the lateral sides of the carapace slightly more bulging, giving the carapace a less pyriform and more ovate shape and the latero-posterior carapace tubercle is a distinct short spine ( Fig. 2B ). Guinot & Richer de Forges (1995: 467) also commented that the ambulatory legs of the specimens from Madagascar and Maldives appeared to be longer and slenderer than the Indian ones, but the accuracy of Alcock’s (1901) figures cannot be ascertained.

The uncertainty over the identity of G. profundorum has been a major problem, and a revision of the genus is only possible once this has been resolved. In this revision, we select a neotype for the species (see discussion for type species below). We also rediagnose G. robusta and G. pacifica based on the type material and describe five new species from Madagascar, Papua New Guinea, Admiralty Islands, Solomon Islands, and the South China Sea.

Figures

Fig. 1. Gordonopsis profundarum (Alcock & Anderson, 1899), syntype female (ca. 13.0 × 9.0 mm), Travancore, India. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax showing buccal cavity, epistome, antennae, antennules, and third maxillipeds. After Alcock (1901: pl. 5 fig. 22).

Fig. 2. Gordonopsis profundarum (Alcock & Anderson, 1899), neotype male (16.0 × 11.0 mm) (NHM 1948.9.7.28), Maldives. A, overall habitus; B, dorsal view of carapace; C, dorso-frontal view of carapace.

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. 6. Gordonopsis profundarum (Alcock & Anderson, 1899), male (16.3 × 24.1 mm) (ZMB 13645), East Africa. A, overall habitus; B, dorsal view of carapace; C, dorso-frontal view of carapace.