Polymesoda expansa   (Mousson,  1849) (Clam)
Organism information awaits expert curation
Class: Bivalvia

Size: Maximum shell length 10 cm, commonly to 7 cm.

Color: Outside of shell chalky white under the greenish to yellowish brown periostracum. Interior chalky or porcelaneous white.

Shell equivalve, trigonal-ovate in outline, inequilateral, distinctly expanded posteriorly. Umbones inflated, in front of the midline of shell. Outer surface of valves concentrically striated, with a faint radial fold running from umbones to posteroventral margin. Periostracum thick and fibrous, the umbones often corroded and showing the shell material. Hinge teeth moderately strong. Anterior and central right cardinal teeth bifid, as well as central and posterior left cardinals. Lateral teeth smooth, 1 anterior and 1 posterior laterals in left valve, as against 2 in right valve. Pallial sinus inconspicuous.

Synonym (s)
Cyrena ceylonica (Chemnitz) 1782
Geloina expansa (Mousson) 1849
Polymesoda proxima (Prime) 1864

Common Name (s)
Economic Importance and Threats
Importance:  Commercial
(Collected as food)

Habitat:  Muddy



Literature Source(s)
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at - http://www.marinespecies.org
  • Poutiers, JM (1998) Bivalves FAO species identification guide for fishery purposes. The living marine resources of the western central Pacific. Volume 1: Seaweeds, corals, bivalves and gastropods FAO, Rome 1 686 pp Available at - http://www.fao.org/docrep/009/w7191e/w7191e00.htm
  • Ng, PKL and Sivasothi, N (eds.) (2001) Guide to mangroves of Singapore Available at - http://mangrove.nus.edu.sg/guidebooks/contents.htm

Page last updated on:2012-11-23

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