First report of two ark shells, Anadara consociata (E. A. Smith, 1885) and A. troscheli (Dunker, 1882) (Arcidae: Anadarinae) from Indian waters with notes on morpho-taxonomy of some related species from east coast of India Author Tudu, Prasad Chandra Marine Aquarium and Regional Centre, Zoological Survey of India, Digha - 721428, West Bengal, India; tuduprasad. c @ zsi. gov. in Author Yennawar, Prasanna Freshwater Biology Regional Centre, Zoological Survey of India, Hyderabad - 500048, Telengana, India Author Mohapatra, Anil Marine Aquarium and Regional Centre, Zoological Survey of India, Digha - 721428, West Bengal, India; tuduprasad. c @ zsi. gov. in & Estuarine Biology Regional Centre, Zoological Survey of India, Gopalpur-on-Sea - 761002, Odisha, India text Records of the Zoological Survey of India 2019 119 1 journal volume 10.26515/rzsi/v119/i1/2019/141303 2581-8686 10913709 1. Anadara antiquata ( Linnaeus, 1758 ) ( Fig. 2 ; a & b) 1758. Arca antiquata Linnaeus , 694 1844. Arca creanata Reeve , sp. 51 1844. Arca hankeyana Reeve , sp. 68 1844. Arca maculosa Reeve , sp. 24 1998. Anadara (Anadara) antiquata : Evseev & Lutaenko, 8. pl. 1, fig. J 1998. Anadara antiquata : Poutiers, 146 2010. Anadara antiquata : Ramakrishna & Dey, 62 2017. Anadara antiquata : Subba Rao, 58 Material examined: 1ex, Gopalpur ( 19°15.449’N and 084°54.559’E ), 3-II-2008 , coll. P. Yennawar , ( Reg. No. MARC / ZSI M3556 ) ; 1ex, Rameswaram ( 09°16.867’N and 079°18.879’E ), 7-IX-2014 , coll. P.C. Tudu , ( MARC / ZSI M4143 ) ; 2ex, Tuticorin ( 08°47.575’N and 078°09.636’E ), 9-IX-2014 , coll. P.C. Tudu , ( MARC / ZSI M4145 ) . Description: Shell medium in size (L up to 51mm & H up to 45mm ), equivalve, solid, equilateral, obliquely ovate and elongate in outline, posterior margin nearly straight, extending along the postero-ventral corner; anterior margin convex, smoothly rounded ventrally, ventral margin nearly straight. Umbones much inflated, situated rather forwards, cardinal area narrow and elongate. Radial ribs 34-44 in number, ribs twice as wide as their interspaces, arcuated in cross section and ornamented with regular ridges. Ligamental area triangular, without ligamental grooves, its maximal wide situated posterior of the beaks. Beak prosogyre and medium in height; slightly depressed in their middle part, hinge plate thickened, hinge series equal to each other, with the centre posterior of the beaks. No byssal gape. Periostracum of the radial ribs brown in colour, squamated, long cilia in the space between ribs, coarse and velvety. Outside of shell white in colour covered with periostracum, inner side white and light yellow in the umbonal cavity. Distribution: In India : Andaman and Nicobar Islands , Andhra Pradesh , Goa, Gujarat , Kerala , Maharashtra , Odisha , Tamil Nadu (Ramakrishna and Dey, 2010 ); Elsewhere: Australia and New Caledonia , East coast of Africa, Japan , Hawaii, Red Sea ( Evseev and Lutaenko, 1998 ; Poutiers, 1998 ), Singapore ( Tan and Woo, 2010 ), China , Philippines , Vietnam ( Evseev and Lutaenko, 1998 ), Madagascar ( Poutiers, 1998 ), Indonesia , Myanmar , Mauritius , Sri Lanka , Zanzibar (Ramakrishna and Dey, 2010 ), East Africa to Central Pacific ( Tebano and Paulay, 2000 ). Remarks : According to Evseev and Lutaenko (1998) , Tebano and Paulay (2001) and Poutiers (1998) , the range of radial ribs for this species is 35-40; 35-39 and up to 44 respectively. Here, our specimen has range from 34 to 35, hence, it is considered that numbers of radial ribs for this species is 34-44.