Meretrix Lamarck, 1799

Rupavath, Rajendar Kumar, Rajan, Rajkumar & Jegadeesan, Vanishree, 2021, Short Communication Range extension and first record of Meretrix lusoria (Röding, 1798) (Mollusca: Bivalvia: Veneridae) from Indian coastal waters, Records of the Zoological Survey of India 120 (4), pp. 507-509 : 507-508

Genus Meretrix Lamarck, 1799

Species M. lusoria (Röding, 1798)

Diagnosis: Shell medium in size, sub-trigonal and equilateral. Umbo is very small, inflated on the top of the anterior margin. Posterior region is slightly convex. Posterior dorsal margin is slightly sloping downwards at the posterior end. Hinge plate consists of two cardinal teeth, single lateral tooth and socket. Lunule is weakly defined. Eustcheon is large, very distinct and extends to one third of the shell. Shell exterior is smooth and provided with fine concentric growth lines. Pallial sinus scar shape located near to the posterior adductor muscle scar is unique for because of a “L” pattern. T he “L” pattern is due to the protruding of pallial line scar from the pallial sinus scar.

T he three species of the genus Meretrix Lamarck, 1799 , M. lusoria , M. casta and M. meretrix , have trigonal shaped shell and prominent hinge teeth. T hese species also have larger anterior and smaller posterior adductor muscle scars, and shallow pallial sinus. Meretrix lusoria (Röding, 1798) is variable from the other two in the shell marking, and the postero-dorsal margin much longer than antero-dorsal margin.

Colour: T he inner side of the shell is pale white with the internal border shaded in dark violet coloration. T he exterior is brownish with thick ‘W’ shaped wavy patterns.

Distribution: Meretrix lusoria is native to estuaries and coastal waters of Asia, from China (Hainan to the Bohai Sea), Korea, and Japan, as far north as Mutsu Bay on the tip of Honshu ( Chung 2007; Chen et al., 2009). T his species is also reported from Sri Lanka, Malaysia, Singapore, T hailand and Taiwan ( Yamakawa et al., 2008; Tan & Woo, 2010; Hamli et al., 2016). It is reported for the first time from Indian Waters.