Anadara pilula ( Reeve, 1843 )

Tudu, Prasad Chandra, Yennawar, Prasanna & Mohapatra, Anil, 2019, 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, Records of the Zoological Survey of India 119 (1) : -

6. Anadara pilula ( Reeve, 1843) ( Fig. 3 ; f & g)

1843. Arca pilula Reeve , sp. 8

1998. Scapharca pilula : Poutiers, 156

2010. Anadara (Scapharca) pilula : Ramakrishna & Dey, 68 2017. Anadara pilula : Subba Rao, 61

Material examined: 1ex, Puri (19°47.416’N and 085°49.346’E), 24-III-2007, coll. P. Yennawar ( MARC / ZSI M3570 ) ; 1ex, Gopalpur (19°15.450’N and 084°54.557’E), 27-III-2007, coll. P. Yennawar ( MARC / ZSI M3568 ) ; 3ex, Chandrabhaga (19°51.576’N and 084°06.409’E), 31-I-2008, coll. P. Yennawar ( MARC / ZSI M3569 ) ; 2ex, Paradip (20°15.115’N and 086°39.283’E), 28-II-2008, coll. P. Yennawar ( MARC / ZSI M4154 ) ; 2ex, Paradip (20°17.322’N and 086°42.596’E), 28-VI-2012, coll. P.C. Tudu ( MARC / ZSI M4151 ) ; 2ex, Paradip (20°17.500’N and 086°42.720’E), 27-IX-2012, coll. P.C. Tudu (Reg. No. MARC / ZSI M3666 ) ; 2ex, Chilka New Mouth (19°

39.486’N and 085° 31.050’E), 19-III-2013, coll. A. Mohapatra ( MARC / ZSI / M3647 ) .

Description: Shell of medium in size (L up to 22.9mm and H up to 21.9mm), strongly inflated, sub-rounded, inequivalve; anterior margin short and slightly convex, ventral side narrowly arcuated, posterior margin nearly straight, with the postero-ventral side somewhat elongated in adults. Radial ribs narrow, ornamented with small nodules which look like crosses and with closely situated ridges that slope to the beak more steeply than to the ventral margin; nodules absent in the middle field of the right valve; number of ribs 23-24. Interspaces of ribs wide, beak prosogyrate and high, narrow, nearly touching the hinge line. No byssal gape. Ligamental area wide, trigonal, ligament ampidetic and equilateral, without chevron grooves. Hinge plate narrow, teeth small, transversal in the middle part and inclined near the edges of the plate, border of teeth series shifted somewhat posteriorly from the beak. Periostracum thin and brown.

Distribution: In India; Andaman and Nicobar Islands, Tamil Nadu (Ramakrishna and Dey, 2010), Elsewhere; East and South China Seas, Indonesia, Thailand, Pacific Coast of Australia, Malaysia, Vietnam ( Evseev and Lutaenko, 1998), Philippines, Sri Lanka, Papua New Guinea ( Evseev and Lutaenko, 1998; Poutiers, 1998), Taiwan, Queensland, Central India Ocean, Western Pacific ( Poutiers, 1998).

Remarks: This species is often confused with Tegillarca rhombea ( Born, 1778) as both the species having equal range of radial ribs, but differs with having thin, strongly inflated shell, no nodules on radial ribs, interspaces wider than ribs.

Figures

Figure 3. a-b,A. ferriginea (Reeve, 1844), a- exterior of left valve, b- exterior of right valve; c-e, A. inaequivalvis (Bruguière, 1789); c-exterior of left valve, d- exterior of left valve & left valve overlapping the right valve along postero-ventral region, e- umbo; f-g, A. pilula (Reeve, 1843); f- exterior of right valve, g- interior of right valve.