The Ashtamudi Lake short-neck clam: re-assigned to the genus Marcia H. Adams & A. Adams, 1857 (Bivalvia, Veneridae).

The economically valuable bivalve mollusc, known as the short-neck clam, is the major fishery resource of the brackishwater Ashtamudi Lake in Kerala, India. This fishery carries a Marine Stewardship Council certification for sustainability wherein it and all hitherto published reports identify the short-neck clam or yellow-foot clam as Paphiamalabarica (Dillwyn, 1817). It is noted that this name does not conform with current nomenclature and is now correctly referred to Protapesgallus (Gmelin, 1791). Furthermore, it is shown that the identification is also incorrect. Comparative shell morphology of venerid clams of the subfamily Tapetinae from the south Indian coast demonstrates that the short-neck clam in Ashtamudi Lake is Marciarecens (Holten, 1802). Small numbers of M.opima (Gmelin, 1791) were found in Ashtamudi Lake but appear not to be part of, or contribute significantly to, the fishery. The venerid clams Protapesgallus and P.ziczac (Linnaeus, 1758) are not found in Ashtamudi Lake but are inhabitants of the shallow coastal waters of south India. Descriptions of the four confused species M.recens, M.opima, P.gallus, and P.ziczac are given. On the basis of this study, the species involved in Marine Stewardship Council (MSC) certification may be better considered at the generic level of Marcia or at the species level as Marciarecens, the most dominant species in the Ashtamudi Lake clam fishery zone.