Redescription of deep-sea roughy

Phylum: Chordata

Class: Actinopterygii

Order: Beryciformes

Family: Trachichthyidae Bleeker, 1856

Hoplostethus (Leiogaster) rubellopterus Kotlyar, 1980

Collection: Bay of Bengal 11°04′N, 80°13′E, 540 m, 27.08.2010 (FORV SS 279, St. 05); 17°09′N, 83°25′E, 567 m, 02.09.2010 (FORV SS 279, St. 23); 17°03′N, 83°17′E, 560 m, 02.09.2010 (FORV SS 279, St. 24); 17°01′N, 83°15′E, 550 m, 02.09.2010 (FORV SS 291, St. 25); 18°49′N, 85°22′E, 614–643 m, 30.10.2011 (FORV SS 291, St. 05); 11°55′N, 80°08′E, 505–785 m, 05.11.2011 (FORV SS 291, St. 10); 11°54′N, 80°08′E, 505–785 m, 5.11.2011 (FORV SS 291, St. 11); 11°54′N, 80°08′E, 528–777 m, 09.11.2011 (FORV SS 291, St. 17); Arabian Sea 09°58′N, 75°53′E, 160 m, 21.08.2012 (FORV SS 305, St. 02); 9°19′N, 75°39′E, 392 m, 02.11.2014 (FORV SS 331, St. 02); 10°58′N, 75°06′E, 351 m, 20.04.2015,   (FORV SS 338, St. 39); 13°00′N, 73°51′E, 328 m, 23.04.2015  (FORV SS 338, St. 47); Andaman Sea 9°33′N, 92°36′E, 625–633 m, 27.01.2015 (FORV SS 334, St. 3A2)

Voucher No.: CMLRE R. C. No. 2790515, 2792310, 2792410, 2910522

Description: Body oval, medium sized, laterally compressed, maximum body width 46–50 % of standard length (SL). Head large, 42–45 % of SL, occupied by moderately deep muciferous cavities covered by a thin skin. Snout rounded with deep muciferous cavities, pre-dorsal length nearly equal to the head length (HL). A flat supra-clavicular spine, and a much stronger one at the angle of the preopercle. Eyes large, diameter 12–14 % of SL. Mouth wide, terminal and obliquely angled, supramaxilla present. Small villiform teeth bands on jaws and on palatines. First dorsal fin with 6 spines and 13–14 soft rays, base length 37–39 % of SL. Anal fin with 3 spines and 9 soft rays, base length 17–18 % of SL. Caudal fin forked with 6 procurrent spines in upper and lower lobes. Pectoral fins reach near end of anal base, with 18 rays, its length 33–38 % of SL. Pelvic fins with 1 spine and 6 rays. Scales thin, ctenoid and deciduous, lateral line possess 27–29 large scales. 9–12 large keeled scales along midventral belly between pelvic and anal fins, forming row of well-developed scutes.

Biological association: None.

Remarks: Hoplostethus (L.) rubellopterus is a commonly occurring species in the deep-sea catches from the upper continental slope (160–800 m) of this region, which is often misidentified and reported as H. mediterraneus Cuvier, 1829.

Distribution: Northern Indian Ocean: off Socotra Island in the Arabian Sea, off Mentawai Island in the eastern equatorial Indian Ocean, southwest and east coast of India and Andaman Islands.

Distribution map:

Identified by: Vinu Jacob

Publication: Vinu, J., Rajeeshkumar, M. P., Sumod, K. S., Meera, K. M., Hashim, M., Sanjeevan, V. N., & Sudhakar, M. (2017). Taxonomic clarification and re-description of two deep-sea roughies of genus Hoplostethus from the Indian Ocean. Marine Biodiversity, 47(2), 491-497.