New record of mesopelagic lanternfish from Western Indian Ocean

Phylum: Chordata

Class: Teleostei J.P. Müller, 1845

Order: Myctophiformes Regan, 1911

Family: Myctophidae Gill, 1893

Diaphus theta Eigenmann & Eigenmann, 1890

Collection: Southwest Indian Ocean, west of Vingt Cinq Island, Mauritius, 14.41°S, 57.26°E, 403 m, 05.10.2015 (FORVSS 344 leg 2, St. 02), Cosmos trawl.

Voucher No.: CMLRE IO/SS/FIS/00486

Description: Fin formula: D 13, A 13, P 10, V 8. Supra-pectoral organ and supra-ventral organ much nearer pectoral and pelvic fin bases than to lateral line. Supra-anal postero-lateral and upper precaudal organs 2–3 diameters below lateral line. SAO series equally spaced and in line with VO5. SAO slightly angular, SAO3 3.0 times its own diameter below lateral line, SAO2 little behind a line through SAO1–3, SAO2–3 interspace slightly greater than that of SAO1–2. First anterior anal organ on level of adjacent ones, occasionally slightly elevated, seldom by a full diameter, last 1 or 2 AOa elevated to form a curve with Pol. Pol and last AOa interspace little larger than those between the other AOa. AOa slightly elevated, Pol 2.0–2.5 times its own diameter below LL. Prc forms a curve with Prc4, 2–3 times its own diameter below LL. Luminous scale at PLO present.

Biological association: None.

Remarks: New record of mesopelagic lanternfish from Western Indian Ocean

Distribution: Eastern Pacific Ocean, Hawaii, Southwest Indian Ocean and Japan. Depth range: 10–3400 m.

Distribution map:

Identified by: Meera K.M.

Publication: Meera K.M., Sanjeevan V.N., Raghu Prakash R., Hashim M. (2024) An updated checklist of myctophids of Western Indian Ocean with 6 new records. Regional Studies in Marine Science, 73: 103450.