Pliocardia “ cordata (Boss, 1968)

Kiel, Steffen, Aguilar, Yolanda M. & Kase, Tomoki, 2020, Mollusks from Pliocene and Pleistocene seep deposits in Leyte, Philippines, Acta Palaeontologica Polonica 65 (3), pp. 589-627 : 611-612

Clade Pliocardia “ cordata group”

Remarks.—“ Pliocardia ” ticaonica reported below was considered very closely related to “ Pliocardia ” cordata (cf., Boss 1968) and hence most likely belong to the “ cordata group” sensu Johnson et al. (2017).

“ Pliocardia ” ticaonica Dall, 1908a

Fig. 23 .

1908 Vesicomya ticaonica sp. nov.; Dall 1908a: 63.

Material.—Three disarticulated specimens from the Pleistocene of Cambantug Point ( NMNS PM 28184–28186).

Dimensions (in mm).— NMNS PM 28185, L = 68.2, H = 52.5.

Remarks.— Huber (2010) considered “ Pliocardia ” ticaonica as a synonym of “ Pliocardia ” indica ( Smith, 1904) .

However, “ Pliocardia ” ticaonica is more elongate than “ P.” indica , and “ P.” indica has a more distinctive lunular incision than “ P. ” ticaonica . Hence, we prefer to retain the name “ P. ” ticaonica . The original description of Vesicomya ticaonica did not include a figure ( Dall 1908a). Although we have not seen the holotype of P. ticaonica , the Philippine Pliocene specimens are indistinguishable from two specimens labeled “ Vesicomya ticaonica ”, housed in the USNM ( USNM 248063 from the Philippines, station 5446 and USNM 229320 from Sibuko Bay, Borneo, Indonesia, station 5592).

When Boss (1968) described “ Pliocardia ” cordata , he considered it “remarkably similar, and probably most closely related, to V. ticaonica Dall ” ( Boss 1968: 735). The two shells are indeed very similar, and we concur with this view. Boss (1968) also considered the late Miocene Waisiuconcha alberdinae Beets, 1942 from Buton Island, Sulawesi, Indonesia, as a precursor or possibly even as a synonym of V. ticaonica . However, whether the much smaller (23 mm) and thin-shelled W. alberdinae is indeed closely related to the thick-shelled “ P.” ticaonica and “ P.” cordata remains to be tested.

Stratigraphic and geographic range.—Early Pleistocene, Leyte, Philippines. Recent: Philippines and Indonesia.

“ Pliocardia ” indica ( Smith, 1904)

Fig. 24 .

1904 Vesicomya indica sp. nov.; Smith 1904: 9.

Material.—One right valve from the Pleistocene of Cambantug Point NMNS PM 28419 (L = 45.9 mm, H = 38.8 mm).

Remarks.—For comments on the synonymy of “ P.” indica and “ P.” ticaonica see above.

Stratigraphic and geographic range.—Early Pleistocene, Leyte, Philippines. Recent: Bay of Bengal.

Figures

Fig. 23. The vesicomyid bivalve “Pliocardia” ticaonica Dall, 1908 from the early Pleistocene Cambantug Point seep deposit in Leyte, Philippines. A. NMNS PM 28186, right valve, outer shell surface (A1), dorsal side (A2), anterior side (A3), inner side showing hinge (A4). B. NMNS PM 28185, left valve, dorsal side (B1), outer shell surface (B2), inner side showing hinge (B3), anterior side (B4).

Fig. 24. The vesicomyid bivalve “Pliocardia” indica (Smith, 1904) from the early Pleistocene seep deposit at Cambantug Point, Leyte, Philippines, NMNS PM 28419, an isolated right valve, seen from the outside (A1) and inside (A2).