Anadara troscheli ( Dunker, 1882 )

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) : -

7. Anadara troscheli ( Dunker, 1882) ( Fig. 4 ; a-g)

1882. Scapharca troscheli Dunker.

1998. Anadara (Scapharca) troscheli : Evseev & Lutaenko, 31

Material examined: 1ex, Gopalpur (19°15.450’N and 084°54.557’E), 27-III-2007, coll. P. Yennawar ( MARC / ZSI M3550 ) ; 1ex, Gopalpur (19°15.449’N and 084°54.559’E), 2-I-2008, coll. P. Yennawar ( MARC / ZSI M3551 ) ; 2ex, Kakinada (16° 54.492’N and 082° 14.370’E), 25-VI-2013, coll. A Mohapatra & PC Tudu, ( MARC / ZSI M3552 ) ; 2ex, Pulicat Lake (13˚25’ 27” N and 80˚19’ 26” E), 12-XII-2014, coll. PC Tudu, ( MARC / ZSI / M4088 ) .

Description: Shell medium in size (L up to 69.8mm and H up to 57.9mm), stout, subtrigonal in shape and high, with an elongated posterior margin and a prominent posterior-ventral fold; anterior margin narrow, smoothly joined to the slightly convex ventral margin; posterior margin broad, nearly straight. Radial ribs narrow, rectangulate in cross-section, bear coarse growth lines or irregular knobs on flat tops in the right valve, and are rounded, with crossing ridges in the left valve, especially well exposed on the anterior and central field of the valve; number of ribs 22-25; interspaces between ribs wider than ribs. Ligamental

area concentric, its maximal width situated under the beak, chevron grooves regular and strong in the posterior part, and short, uneven with posterior grooves in the anterior part. Beak prosogyre, narrow and high, with a prominenet postero-ventral fold. Hinge plate wide, the posterior teeth series somewhat longer than the anterior series; the border between the anterior

and posterior series is situated slightly posterior to the beak. Periostracum brownish and ciliated.

Distribution: In India: Andhra Pradesh, Odisha and Tamil Nadu (present report); Elsewhere: Japan, South China Sea, Vietnam ( Evseev and Lutaenko, 1998), Thailand ( Meyer et al., 2008).

Remarks: Present report is the first ever report of A. troscheli ( Dunker, 1882) from Indian waters, from Andhra Pradesh, Odisha and Tamil Nadu state. This species may be overlooked with morphologically similar species, Tegillarca rhombea ( Born, 1778) , but this species having wider interspaces between ribs or same as in ribs width and lesser number of radial ribs (22-25) compared to narrower interspaces than ribs in later and more number of radial ribs (24-27).

Figures

Figure 4. a-g,A. troscheli (Dunker, 1882); a-b, interior right & left valve, c- exterior right valve, d- umbo, e- anterior, f- posterior & g- ventral view of shell.