Trisidos tortuosa   (Linnaeus,  1758) (Clam)
Organism information awaits expert curation
Class: Bivalvia

Image copyrights: seashellhub

Color: Shell white, very faintly tinged with pale brown.

Shell inequivalved, twisted, medially depressed; anterior side of shell acuminated at upper part, rounded beneath, posterior side angulated, very widely expanded, valves with an oblique keel running from the umbo down to the lower margin keel feebly serrated, shell with the front margin; distinctly narrower than the hind one. The keel is sometimes, especially in young shells, less sharply angular. A distinct and characteristic double scar present on the interior of the shell running from the umbo to the top of the hind margin running from the shell.
Shell whitish with pallial line simple, posterior adductor muscle scar larger than the anterior adductor muscle scar, hinge teeth larger and slightly oblique towards centre. The shell bears an elegant sculpture of moderately strong, close set, radiating ridges conspicuosly decussated by strong, concentric growth striae. The radial ridges are almost entirely absent from the area behind the keel in the left valve.

Synonym (s)
Arca tortuosa Linnaeus, 1758
Parallelepipedum fauroti Jousseaume, 1888
Trisidos tortuosa addita Iredale, 1939
Trisidos tortuosa cingalena Iredale, 1939
Trisidos yongei Iredale, 1939
Trisidos yongei archeri Iredale, 1939
Trisidos yongei lamyi Iredale, 1939
Trisidos yongei reevei Iredale, 1939

Common Name (s)
Economic Importance and Threats

Habitat:  Coastal


• Tamil Nadu, Dhanushkodi INDIA
• Tamil Nadu, Gulf of Mannar (Lat: 78.13) (Long: 8.58) INDIA (Record: 01/1994- 12/1995)
• Tamil Nadu, Gulf of Mannar (Lat: 79.5) (Long: 9.33) INDIA (Record: 01/1994- 12/1995)
• Andaman and Nicobar Islands, Andamans INDIA

Literature Source(s)
  • Samuel, VD; Chacko, D and Edward, JKP (2005) Preliminary study on the molluscan diversity of “the lost world’’– Dhanushkodi, east coast of India Proceedings of the National Seminar on Reef Ecosystem Remediation SDMRI Special Research Publication No.9 54-58 Available at -
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Available at -
  • Hameed, PS and Somasundaram, SSN (1998) A survey of bivalve molluscs in Gulf of Mannar, India Indian Journal of Fisheries Indian journal of Fisheries for the Indian Council of Agricultural Research, Kochi, India 45(2) 177-181 Available at -
  • Subba Rao, NV and Dey, A (2000) Catalogue of marine molluscs of Andaman and Nicobar Islands Occasional paper no 187 Records of the Zoological Survey of India ZSI 1-323 Available at - NCL, Pune
  • Shanmugam, A; Rajagopal, S and Nazeer, RA Common bivalves of Parangipettai coast Available at - NIO, Goa

Page last updated on:2012-11-27

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