Gordonopsis profundarum ( Alcock & Anderson, 1899 )

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 : 268-277

Gordonopsis profundarum ( Alcock & Anderson, 1899)

( Figs. 1–8)

Homola profundorum Alcock & Anderson, 1899: 5 ; Alcock, 1899: 10, pl. 1 fig. 2.

Homola (Paromola) profundorum – Alcock, 1901: 64, pl. 5 fig. 22; Doflein, 1904: 16, pl. 7 figs. 1, 2.

Paromola profundorum – Ihle, 1913: 57; Serène & Lohavanijaya, 1973: 27.

Paromola profundarum – Gordon, 1950: 223; Griffin, 1965: 87.

Gordonopsis profundorum – Guinot & Richer de Forges, 1995: 463, figs. 63d–h, 64A, B.

Gordonopsis aff. profundorum – Guinot & Richer de Forges, 1995: 467 (in part).

Gordonopsis profundorum – Ng et al., 2008: 40.

Material examined. Neotype: male (11.0 × 16.0 mm) (here designated) (NHM 1948.9.7.28), stn 153, 4°42′36″N,

72°50′24″E – 4°45′36″N, 72°52′12″E, Maldives, 256–293 m, dredge, coll. John Murray Expedition, 4 April 1934. – 1 male (16.3 × 24.1 mm) ( ZMB 13645 ) , stn 258, 2°58.5′N, 46°50.8′E, off Somalia, East Africa , 1,362 m, coll. Deutsche Tiefsee Expedition, coll. Valdivia , 1898–1899.

Diagnosis. Male: carapace longitudinally ovate, width to length ratio 0.68–0.69, distinctly wider posteriorly than anteriorly; dorsal carapace surface with well-defined regions, separated by broad, deep grooves; lateral margin distinctly convex; dorsal parts with numerous scattered soft setae, not obscuring surface; lateral parts with denser setae, partially obscuring surface, relatively denser on hepatic, pterygostomial, and suborbital regions ( Figs. 1 A–C, 2A–C, 3A, B, 6A–C, 7A, B). Rostrum relatively long, sharp, with 2 long, obliquely directed pseudorostral spines, just shorter than rostrum ( Figs. 1B, 2B, 6B). Supraorbital margin relatively narrow, C-shaped; pseudorostral spines directed obliquely laterally at angle of about 45° to median axis ( Figs. 1B, 2B, 6B). Eyes with short ocular peduncle, cornea prominent; no discernible orbit ( Figs. 1B, 2B, 6B). Hepatic region gently inflated, with short obliquely directed spine ( Figs. 1B, 2B, 6B). Gastric region without spines ( Figs. 1B, 2B, 6B). Gastric groove well marked, with distinct ovate gastric fossae just above ( Figs. 1B, 2B, 6B). Cardiac region swollen; branchial region inflated, with distinct branchio-cardiac grooves ( Figs. 1B, 2B, 6B). Latero-posterior tubercle on carapace large, prominent, sharp ( Figs. 1B, 2B, 6B). Base of antenna with strong spine ( Figs. 1C, 3D, 7D). Antennal flagellum short, second and third articles thick, setose. Epistome triangular ( Figs. 1C, 3D, 7D). Third maxilliped pediform, merus elongate with angular external angle ( Figs. 1C, 3C, 7C). Chelipeds long; fingers long, about half length of palm; surface gently rugose with scattered small granules; carpus longitudinally ovate, outer margin with 3 spines and 2 or 3 spinules, distal edge with 1 spine, inner margin with 2 or 3 spines and 2 or 3 spinules, dorsal surface with low ridge lined with 6–9 low or sharp granules, never spines; merus triangular in cross-section, relatively long, curved, dorsal margin with 5 or 6 spines and distal 2 spines bracketing chela, outer ventral margin with 7–9 spines or spinules, inner ventral margin with 5 or 6 spines or spinules ( Figs. 1A, 2A, 3 E–I, 6A, 7E–G). Ambulatory legs long; basisischium with small granules, not spines; P2 merus with 5 spines or spinules on dorsal margin (excluding 1 distal spine), ventral and subventral margins with 1–4 spinules; P3 merus with 5 or 6 spines or spinules on dorsal margin (excluding 1 distal spine), ventral and subventral margins with 0–3 spinules; P4 merus with 3 or 4 spines or spinules on dorsal margin (excluding 1 distal spine), ventral margin with 1 spine or spinule, outer surface with 1 strong proximal spine or spinule ( Figs. 1A, 2A, 5 A–C, 6A, 8F–H). 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 7–9 spines, that of dactylus with 7 or 8 spines ( Figs. 4A, 5 D–F, 8A, I, J). Outer margins of P2–P4 coxae smooth, unarmed ( Figs. 4 E–G, 8D, E). Telson triangular, with convex lateral margins, distal part distinctly narrowing ( Figs. 4 B–D, 8B, C). G1 short, stout, distal part subconical with convex tip ( Figs. 4H, 8K). G2 stout, tubular, subequal to G1 length, distal portion cup-shaped ( Figs. 4I, 8L).

Description of male neotype. Male: carapace longitudinally ovate, width to length ratio 0.69, distinctly wider posteriorly

than anteriorly; dorsal carapace surface with well-defined regions, separated by broad, deep grooves; lateral margin distinctly convex; dorsal parts with numerous scattered soft setae, not obscuring surface; lateral parts with denser setae, partially obscuring surface, relatively denser on hepatic, pterygostomial, and suborbital regions ( Figs. 1 A–C, 2A–C, 3A, B, 6A–C, 7A, B). Rostrum relatively long, sharp, with 2 long, obliquely directed pseudorostral spines, shorter than rostrum ( Figs. 1B, 2B, 6B). Supraorbital margin relatively narrow, C-shaped; pseudorostral spines directed anterolaterally at angle of about 45° to median axis ( Figs. 1B, 2B, 6B). Eyes with short ocular peduncle, cornea prominent; no discernible orbit ( Figs. 1B, 2B, 6B). Hepatic region gently inflated, with short obliquely directed spine ( Figs. 1B, 2B, 6B). Gastric region without spines, each mesogastric region with median patch of small granules ( Figs. 1B, 2B, 6B). Gastric groove well marked, with distinct ovate gastric fossae just above ( Figs. 1B, 2B, 6B). Cardiac region swollen; branchial region inflated, with distinct branchio-cardiac grooves ( Figs. 1B, 2B, 6B). Latero-posterior tubercle on carapace distinct, prominent ( Figs. 1B, 2B, 6B). Base of antenna with strong spine ( Figs. 1C, 3D, 7D). Antennal flagellum short, second and third articles thick, setose. Epistome triangular ( Figs. 1C, 3D, 7D). Third maxilliped pediform, merus elongate with angular external angle ( Figs. 1C, 3C, 7C). Chelipeds long; fingers long, about half length of palm; surface gently rugose with scattered small granules; carpus longitudinally ovate, outer margin with 3 spines and 2 spinules, distal edge with 1 spine, inner margin with 2 spines and 3 spinules, dorsal surface with low, uneven ridge lined with 6–8 very low granules; merus triangular in cross-section, relatively long, curved, dorsal margin with 4 spines and 2 spinules, with distal 2 spines bracketing chela, outer ventral margin with 8 or 9 spines or spinules, inner ventral margin with 6 spinules ( Figs. 1A, 2A, 3 E–I, 6A, 7E–G); basis-ischium quadrate, outer margin with 2 spinules, inner margin with 3 spinules, dorsal margin with prominent spine. Ambulatory legs long; basis-ischium with 4 small granules (sometimes very small and almost undiscernible), never with spines; P2 merus with 5 spines or spinules on dorsal margin (excluding 1 distal spine), subventral margin with 4 spinules; P3 merus with 5 spines or spinules on dorsal margin (excluding 1 distal spine), subventral margin with 3 spinules; P4 merus with 3 spines on dorsal margin (excluding 1 distal spine), ventral margin with 1 spinule, outer surface with 1 strong proximal spinule ( Figs. 1A, 2A, 5 A–C, 6A, 8F–H). 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 or 8 spines ( Figs. 4A, 5 D–F, 8A, I, J). Outer margins of P2–P4 coxae smooth, unarmed ( Figs. 4 E–G, 8D, E). Telson triangular, with gently convex lateral margins, distal part distinctly narrowing ( Figs. 4 B–D, 8B, C). G1 short, stout, distal part subconical with gently convex tip ( Figs. 4H, 8K). G2 stout, tubular, subequal to G1 length, distal portion cup-shaped ( Figs. 4I, 8L).

Variation. The latero-posterior carapace tubercles do not appear to vary—both the small female from Maldives and the large East African specimens have similarly sized large ones ( Figs. 2B, 6B); and both have the same carapace shape as well as long ambulatory legs of similar proportions.

Colour. Not known.

Remarks. Alcock & Anderson (1899) named the species “ Homola profundorum ” and also used this spelling in another paper ( Alcock, 1901). Gordon (1950) used the spelling “ profundarum ” for the species but she did not explain why, and other authors have continued to use “ profundorum ” (cf. Ihle, 1918; Guinot & Richer de Forges, 1995; Ng et al., 2008). If the gender of the genus name is masculine or neuter, the species name should be spelled, “ profundorum ”. Gordonopsis , however, is feminine (all names ending in - opsis are feminine under Article 30.1.2 of the zoological code; ICZN, 1999) and so, the correct spelling for the species name is “ profundarum ”.

Alcock & Anderson (1899: 5) described the species on the basis of three young females (size given as about 13.0 × 9.0 mm) collected by the “Investigator” from the Travancore coast (7°17′30″N, 76°54′30″E), from a depth of 430 fathoms (= 796 m). One of these syntype specimens was figured by Alcock (1899: 10, pl. 1 fig. 2; 1901: 64, pl. 5 fig. 22). In the structure of the carapace and chelipeds, the original description and figures agree very well with the two males examined in this study from the Maldives and East Africa. While the armature on the meri of P2–P4 of the type figure agree with the present specimens, the meri and propodi are significantly shorter ( Fig. 1A). This discrepancy in proportions cannot be explained by size alone even though the syntypes are smaller in size than the present material. Specimens of other species in which large and small specimens are known (e.g., G. robusta , Fig. 12) do not show such a substantial difference in proportions. We tried to examine the type material of G. profundarum , all supposedly still in the present Zoological Survey of India (Calcutta) but the material could not be located despite several searches over two years (S. Mitra, personal communication). They are also not in the NHM. The syntypes are thus almost certainly lost.

The only species that has ambulatory meri as short as those figured by Alcock (1899, 1901) (present Fig. 1A) is G. robusta from the Andamans in the eastern Indian Ocean ( Figs. 12A, B, 13G, H); but in this species, the carapace and P2–P5 are prominently more setose ( Fig. 12 A–D) (versus less setose in G. profundarum ; Figs. 1 A–C, 6A–C); the surfaces of the chela are prominently granulated ( Fig. 12E) (versus smooth in G. profundarum ; Figs. 3H, I, 7F); the carpus of the cheliped has more spines ( Fig. 13F) (versus carpus less prominently spinose in G. profundarum ; Figs. 3F, G, 7F, G); the lateral margins of the male telson are uniformly convex ( Fig. 13D) (versus with the proximal part convex but tapering more sharply to the tip in G. profundarum ; Figs. 4B, 8C); and the distal part of the G1 is more elongate with a bifurcate tip ( Fig. 13K) (versus the distal part being shorter with a convex tip in G. profundarum ; Figs. 4H, 8K).

As discussed earlier, the specimens here, referring to G. profundarum s. str. from the Maldives and East Africa, differ from those figured by Alcock (1899, 1901) (present Fig. 1A) only in possessing proportionately longer P2–P5. We are of the opinion that Alcock’s (1899, 1901) figures of the P2–P4 are inaccurate, with the legs probably originally drawn at an angle. In view of the uncertainty of the identity of what is G. profundarum s. str., the loss of the types, and that it is the type species of the genus, there is now a clear need to designate a neotype for the species. To stabilise the taxonomy of the species and genus, we here select a male (11.0 × 16.0 mm, NHM 1948.9.7.28) as the neotype of Homola profundorum Alcock & Anderson, 1899 . This specimen was collected from the Maldives at 4°42′36″N, 72°50′24″E – 4°45′36″N, 72°52′12″E (cf. Sewell, 1935), a site approximately 500 km southwest of the type locality of the original H. profundorum off Travancore. Both sites are in the same basin.

The waters off Travancore and western Indian Ocean are home to two species of Gordonopsis . Gordonopsis alaini , new species, from off Madagascar, has P2–P5 meri and propodi proportions that agree better with those of G. profundarum figured by Alcock (1899, 1901) (present Fig. 1A) but can easily be distinguished by its more triangular carapace shape ( Fig. 9B) (versus more ovate in G. profundarum ; Figs. 2B, 6B); the latero-posterior carapace tubercle is visible only as a low swelling ( Fig. 9B) (versus present as a distinct tubercle in G. profundarum ; Figs. 2B, 6B); the carpus of the cheliped has fewer spines ( Fig. 10 E–G) (versus with numerous spines in G. profundarum ; Figs. 3F, G, 7F, G); and the distal part of the G1 is very broad ( Fig. 10H) (versus G1 distal part narrow in G. profundarum ; Figs. 4H, 8K). See general discussion for comparisons with other congeners.