Tegillarca rhombea ( Born, 1778 )

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) : -

11. Tegillarca rhombea ( Born, 1778) ( Fig. 5 ; g & h)

1780. Arca rhombea Born ,

1843. Arca rhombea Reeve , sp. 12

1965. Arca rhombea : Kundu, 40

1988. Anadara (Tegillarca) rhombea : Narasimham, 203

2010. Anadara rhombea : Ramakrishna & Dey, 64

2017. Tegillarca rhombea : Subba Rao, 64

Material examined: 3ex, Chandrabhaga (19°51.576’N and 084°06.409’E), 25-III-2007, coll. P. Yennawar ( MARC / ZSI M3560 ) ; 1ex, Gopalpur (19°15.450’N and 084°54.557’E), 26-III-2007, coll. P. Yennawar ( MARC / ZSI M3561 ) ; 4ex, Gopalpur (19°15.259’N and 084°54.343’E), 27- III-2007, coll. P. Yennawar ( MARC / ZSI M3557 ) ; 3ex, Chandrabhaga (19°51.576’N and 084°06.409’E), 31- I-2008, coll. P. Yennawar ( MARC / ZSI M3559 ) ; 11ex, Gopalpur (19°15.449’N and 084°54.559’E), 2-II-2008, coll. P. Yennawar ( MARC / ZSI M3562 ) , 10ex, Gopalpur (19°15.338’N and 084°54.434’E), 3-II-2008, coll. P. Yennawar ( MARC / ZSI M3558 ) ; 1ex, Talsari (21˚36’

1.74” N and 87˚27’ 12.86” E), 21-VIII-2008, coll. P.C. Tudu ( MARC / ZSI 4150 ) ; 33ex, Chilka New Mouth (19° 39.486’N and 085° 31.050’E), 19-III-2013, coll. A. Mohapatra ( MARC / ZSI / M3645 ) ; 4ex, Pulicat Lake (13˚25’ 27” N and 80˚19’ 26” E), 12-XII-2014, coll. P.C. Tudu ( MARC / ZSI / M4087 ) .

Description: Shell medium in size (L up to 40.4mm & H up to 37.3mm), equivalve, thick and solid; somewhat heart shaped, convex, much inflated and distinctly equilateral; dorsal margin straight, anterior end rounded sloping ventrally, posterior end rounded and obliquely produced in the ventral side; ventral margin concave. Ligamental area rather wide, rhomboidal and with brownish black chevron markings; consisting one complete marginal chevron, with numerous vertical markings. Hinge long, slightly concave with taxodont dentition in single straight series. Tooth 35-52 become slightly longer at the extremes; the anterior and posterior ones slightly curved forward and backwards respectively; remaining teeth perpendicular to the hinge line. Beaks prosogyrate; umbones widely separated. Radial ribs 21- 27 in number, high and squarish solid; sculptured with closely set transverse flat nodules; posterior 9-10 ribs without nodules, interspaces of the nodules much smaller than nodules; interspaces of the ribs smaller than ribs. Periostracum dark brown, smooth for major part except

for the posterior part where it is hairy. Inner shell white in colour. Ventral, anterior and posterior margins of the valves with strong crenulations corresponding to the external ribs. Impressions of the external ribs not visible in inner side of the valves. Pallial line without siphonal indentation, palial sinus absent. Posterior adductor scar elongately squarish and anterior scar similar but smaller.

Distribution: India: All maritime states including Andaman and Nicobar Island (Ramakrishna and Dey, 2010); Elsewhere: Chinese Seas ( Reeve, 1843; Evseev and Lutaenko, 1998), Indonesia, Java, Pakistan ( Subba Rao et al., 1991), Sri Lanka ( Reeve, 1843; Subba Rao et al., 1991), Philippines, Pleistocene deposits of Taiwan ( Evseev and Lutaenko, 1998), Indian Ocean ( Narasimham, 1988).

Remarks. This species is morphologically similar with, A. troscheli ( Dunker, 1882) but having narrower interspaces and more number of radial ribs (24-27) compared to wide interspaces and lesser number of radial ribs (22-25) in later.

Figures

Figure 5. a-b,Mosambicarca erythraneonensis (Jonas in Philippi, 1851), a-exterior of left valve, b- interior of left valve, c-d, Tegillarca granosa (Linnaeus, 1758); c- exterior of right valve, d- internal view of right valve; e-f, T. nodifera (Martens, 1860); e-exterior of left valve, f- interior of left valve; g-h, T. rhombea (Born, 1778); g-exterior of left valve, h-interior of left valve.