New Report and Taxonomic Comparison of Anadara and Tegillarca Species of Arcidae (Bivalvia: Arcoidea) from Southern Coast of India

Arcacea family is economically important group of animals. Most of the species in this family are misplaced into invalid subgenera and Indian arcids are wanted a revision in systematic positon. In the case of Arcidae family, all of the species are treated under Anadara as main genera, however, some authors considered that the Tegillarca genus is only a sub genus of Arcidae family. Anadara is the commercially important genus of bivalves of Arcidae family. These two genera are confused by many taxonomists and some considered that the morphometric changes of Tegillarca are only the habitual adaptation. But the collected samples from the same habitat from the southern part of India is clearly demarked the distinction between Anadara species and Tegillarca species. In this paper the differences between these two genera are illustrated with the help of specimens from the same habitat and with the help of taxonomic literature of these genera. Species level classification was done based on the morphometric characters like peculiarities of (i) periostracum, (ii) cardinal area, (iii) umbo, (iv) adductor muscle scar and (v) pallial line. The specimens were collected from Neendakara, Vizhinjam and Kovalam along with the south west coast and Thiruchendur in Tamil Nadu, south east coast of India. The new records clearly indicate the abuandance and richness of these species of bivalves in the southern part of India. Four species are newly reported and they are Anadara pumila (Dunker, 1868), Anadara trapezia (Deshayes, 1839), Tegillarca nodifera (Martens, 1860) and Tegillarca aequilatera (Dunker, 1868). The newly reported specimens from the southern tip of India were deposited in the Marine Biodiversity Museum, Central Marine Fisheries Research Institute (CMFRI) Kochi, Kerala, India.