Archivesica cf. kawamurai ( Kuroda, 1943 )

Archivesica cf. kawamurai ( Kuroda, 1943) View in CoL

Fig. 19 View Fig .

Material.— One juvenile shell, SMF373080 About SMF ; one adult valve, SMF373081 About SMF ; one adult valve, SMF373078 About SMF ; one adult valve, SMF373079 About SMF ; one juvenile valve, SMF373077 About SMF . Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth, 16.18–16.88 mbsf level, core NGHP-01-12A; Upper Pleistocene. For additional material see Table 1 GoogleMaps .

Description.—Large, solid vesicomyid shell, equivalve, inequilateral. Outline oblong-ovate, weakly protruding umbo at 25% from anterior margin, all margins convex, anterior and posterior most convex. Sculpture with numerous irregular coarse growth lines. Lunule not conspicuous, long lanceolate escutcheon. Length largest valve 43 mm

Remarks.—The large size, outline, sculpture and hinge of our specimens suggest that they are probably conspecific with Archivesica kawamurai , a species described off Japan, Sagami Bay ( Kuroda 1943); the species also known from the Pliocene and Recent from various locations around Japan ( Kuroda 1943; Amano and Kiel 2010: 158) and around Taiwan ( Kiel et al. 2024: 10, figs. 8P–R). Archivesica kawamurai can be identified by the hinge and the widely convex ventral margin, a feature found in the holotype ( Amano and Kiel 2010: 156–158, fig. 18). Many species in Archivesica have a straightened or slightly concave ventral margin. A morphologically similar species to our specimens is Archivesica arctica Hansen et al., 2017 , from off NW Svalbard; this species has a similar outline and hinge, and its anterior margin seems less convex ( Hansen et al. 2017). Calyptogena marissinica Chen et al., 2018 , has a similar outline to our specimens, but this species has a different hinge with symmetrical cardinal teeth 2a, b of equal strength; our species has a strong 2b tooth and a weak 2a tooth, which are placed obliquely ( Chen et al. 2018: figs. 2, 3).