New species of deep-water Thyasiridae (Mollusca: Bivalvia) from the northern Indian Ocean

Phylum: Mollusca

Class: Bivalvia Linnaeus, 1758

Order: Lucinida Gray, 1854

Family: Thyasiridae Dall, 1900 (1895)

Species: Ascetoaxinus ravichandrani Ravinesh, P. G. Oliver & Saravanane, 2024

Collection: off Kanyakumari, Tamil Nadu, South India; 07°24.367′N, 076°46.889′E; dredged at 1007–1038 m; 4 April 2024.

Voucher No: CMLRE IO/SS/BIV/00001, IO/SS/BIV/00002, IO/SS/BIV/00003 and IO/SS/BIV/00004

Description: Shell to 21.8 mm long, very thin, brittle, translucent, equivalve, moderately tumid, strongly inequilateral. Beaks prosogyrate located close to anterior margin. Outline obliquely subovate; anterior margin almost straight, bounding a large excavated lunule with toothed margin; ventral margin long, almost straight; posterior margin broad, sulcate. Posterior dorsal sinus distinct; submarginal sinus indistinct. Posterior sulcus sharply defined, relatively narrow; submarginal sulcus clearly delineates a raised escutcheon. Posterior ventral slope, located anterior to posterior sulcus, slightly flattened, creating a weak secondary ridge. Hinge teeth lacking; ligament partially sunken, relatively short, its length less than half that of escutcheon. Sculpture of well-defined growth lines; lunule margin with six weak, rounded teeth. Adductor-muscle scars prominent; anterior scar elongate, mostly separate from pallial line, parallel to ventral margin; posterior scar ovate. Shell creamy-white or white.

Biological association: None

Remarks: New species of deep-water Thyasiridae (Mollusca: Bivalvia) from the northern Indian Ocean

Distribution: Off Kanniyakumari, Tamil Nadu, India.

Distribution map:

Identified by: Ravinesh, R.

Publication: Ravinesh, R., Oliver, P. G., Saravanane, N. (2024). Ascetoaxinus ravichandrani sp. nov., a new species of deep-water Thyasiridae (Mollusca: Bivalvia) from the northern Indian Ocean. Journal of Conchology. 45(1): 125-134. https://doi.org/10.61733/jconch/4514