Tenagopelta potens ( Davie and Richer de Forges, 2013 )

Islam, Atikul, Banerjee, Abhishek, Wati, Sisca Meida, Banerjee, Sumita, Shrivastava, Deepti & Srivastava, Kumar Chandan, 2022, Crabs (Crustacea, Decapoda) from the Sea off East and Southeast Asia Collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 2. Timor Sea, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (1), pp. 5-24 : 19-21

Tenagopelta potens ( Davie and Richer de Forges, 2013)

( Fig. 8A–C )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 26 (Timor Sea; 09°27.0′S, 127°58.6′E –09°285.0′S, 127°56.1′E, 610–690 m depth), 3 m beam trawl; June 19, 1972; 1 ♀ (NSMT-Cr 29417: CB 8.2 mm, CL 7.2 mm).

Remarks. In the monograph on the family Chasmocarcinidae Serène, 1964 , Ng and Castro (2016) revised all the known species of the worldwide, with keys to the subfamilies, genera and species. The descriptions are elaborate, with many photographs of numerous specimens from many localities. Following this monumental work, a female specimen at hand was identified, though tentatively, as Tenagopelta potens ( Davie and Richer de Forges, 2013) in the subfamily Chasmocarcininae Serène, 1964 , in which the antennular peduncle is so swollen that the flagellum cannot be folded into the fossa. Among 11 genera distinguished, the genus Tenagopelta was characterized by the combination of the following characters: 1) The eyestalks are mobile within the orbits; 2) the carapace is subquadrate; 3) the lsupplementary platez is wide, stretching across exposed part of the male thoracic sternum not covered by pleon, reaching the sterno-pleonal cavity, and the G1 is normal, not strongly twisted; 4) the region immediately below the orbital margin is smooth, without a separate ridge; 5) the pollex of the minor chela has many small, approximately equal teeth; 6) the carapace is conspicuously globose, with a convex dorsal surface; 7) the G2 is distinctly longer than the G1.

The type species of Tenagopelta is T. pacifica Ng and Castro, 2016 from the Philippines and Indonesia, and the congeneric species are T. potens ( Davie and Richer de Forges, 2013) from Papua New Guinea, Vanuatu, New Caledonia and Queensland and T. brachyphallus Ng and Castro, 2016 from Western Australia. According to the original description and the key, the males of T. pacifica and T. potens may be readily distinguished from each other by the different shape of the G1 (elongated and slender distal two-thirds in T. pacifica , and short and stout distal half in T. podens ). However, most of the external characters described for the two species are precisely applicable to the female at hand. The carapace is subtrapezoidal and globose in both T. pacifica and T. podens , with arcuate, unarmed anterolateral margins without distinct lobes or teeth, the proportions of the carapace (CB: CL) being 1.15–1.25 (Davie and Richer de Forges) and 1.1– 1.2 (Ng and Castro) in T. podens , and 1.0– 1.2 in T. pacifica . As such, the shape of the carapace and the carapace proportional difference seem to be not specific. However, Ng and Castro (2016) recorded that the carapace dorsal and ventral surfaces and the pereiopods are covered by a short tomentum in T. potens , and that the carapace margin is provided with short setae in T. pacifica . The setation may be variable individually, developmentally and sexually, but is currently considered as one of the taxonomic criteria. The carapace dorsal surface of the present female is shallowly divided into regions by the longitudinal furrows along both sides of the gastric and cardiac regions ( Fig. 8B ), agreeing with the images of the dorsal and antero-dorsal views of the holotype given by the original authors ( Davie and Richer de Forges, 2013, figs. 1A, 3). A topotypic male should, however, be examined for definite identification.

Distribution. Known from the West Pacific (Northeast Queensland; Papua New Guinea; Vanuatu; New Caledonia), 95–970 m depth.

Figures

Fig. 8. A–C: Tenagopelta potens (Davie and Richer de Forges), female (NSMT-Cr 29417: CB 8.2mm×CL 7.2mm) from sta. 26 (Timor Sea, 610–690m depth). D: Trichopeltarion alcocki Doflein, female (NSMT-Cr 29269: CB 18.8mm excluding lateral spines×CL 22.0mm excluding rostrum) from sta. 33 (Off Sahul Shelf, 535–547m depth).