Pliocardiinae Woodring, 1925

Subfamily Pliocardiinae Woodring, 1925 View in CoL

Remarks.—The subfamily currently contains 19 genera. Species from all genera in Pliocardiinae are known to harbour chemosymbiotic bacteria (e.g., Krylova et al. 2018). In the Krishna-Godavari Basin fossil material species in the genera Pliocardia Woodring, 1925 , Callogonia Dall, 1889a , and Archivesica Dall, 1908a , are present.

Genus Pliocardia Woodring, 1925 View in CoL

Type species: Anomalocardia bowdeniana Dall, 1903 , by original designation; Pliocene , Jamaica .

Pliocardia cf. solidissima ( Prashad, 1932) View in CoL

Fig. 18A View Fig .

Material.— One valve ( SMF373088 About SMF ) from Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth, 16.68 mbsf level, core NGHP-01-12A; Upper Pleistocene GoogleMaps .

Description.—Medium-sized, solid vesicomyid shell, equivalve, inequilateral. Outline oblong-ovate, strongly protruding umbo directed anteriorly, antero-dorsal margin concave, postero-dorsal and ventral margins weakly convex, anterior margin most convex, posterior widely convex. Sculpture with numerous irregular coarse growth lines. Elongated yet widely oval lunule, narrow elongated escutcheon. Internally, large teeth and hinge plate, pallial sinus absent. Length 36 mm.

Remarks.— Prashad’s (1932) species is determined by its medium size, thick globose shell, elongated trapezoidal outline, demarcated lunule, hinge and pallial line without sinus. The type locality is from off Bali, Indonesia ( SIBOGA sta. 18, 7°28.2’ S, 115°24.6’ E, 1018 m). A similar species is Pliocardia kuroshimana ( Okutani et al., 2000) , which is known in the Western Pacific off Japan ( Okutani et al. 2000) and in the Miocene on Leyte, Philippines ( Kiel et al. 2020). Another similar species is Pliocardia atalantae ( Cosel & Olu, 2009) from off western Africa. Pliocardia indica ( Smith, 1904) also lives in the Bay of Bengal ( Smith 1904: 9; Huber 2010) in 767–1985 m. Pliocardia indica has a convex ventral margin, whereas our specimen has a flattened ventral margin and a trapezoidal outline.