Pliocardia kuroshimana ( Okutani, Fujikura, and Kojima, 2000 )

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 : 610

Pliocardia kuroshimana ( Okutani, Fujikura, and Kojima, 2000)

Fig. 22 .

2000 Vesicomya kuroshimana sp. nov.; Okutani et al.: 83–84, figs. 2, 6. 2000 Vesicomya kuroshimana Okutani, Fujikura, and Kojima, 2000 ;

Okutani 2000: 996–997, pl. 496.

Material.— Eight specimens from early Pleistocene nonseep sediments at the tip of Liog-Liog Point ( NMNS PM 28189–28191 and five unnumbered specimens) .

Dimensions (in mm).— NMNS PM 28189, L = 48.0, H = 36.6; NMNS PM 28190, L = 48.0, H = 36.3; NMNS PM 28191, L = 48.0, H = 36.6.

Remarks.—The largest extant specimen is 58.9 mm long ( Okutani et al. 2000) whereas the largest early Pleistocene specimen from Liog-Liog Point is only 48.0 mm long. But morphologically we see no difference between the extant and the Pliocene specimens. This is the first fossil record of “ Pliocardia ” kuroshimana ; despite Japan’s a rich Plio-Pleistocene fossil of chemosymbiotic bivalves, no Pliocardia has been reported from sediments of Plio-Pleistocene age yet ( Amano and Jenkins 2011; Amano et al. 2019). Pliocardia kawadai ( Aoki, 1954) is known from the early to middle Miocene, and Pliocardia? tanakai Miyajima, Nobuhara, and Koike, 2017 is known from the middle Miocene ( Aoki 1954; Miyajima et al. 2017; Amano et al. 2019).

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

Figures

Fig. 22. The vesicomyid bivalve “Pliocardia” kuroshimana (Okutani, Fujikura and Kojima, 2000) from early Pleistocene non-seep deposits at the tip of Liog-Liog Point in Leyte, Philippines. A. NMNS PM 28190, partially broken left valve, anterior side showing lunular incision (A1), inner shell surface and hinge (A2), outer shell surface (A3). B. NMNS PM 28191, left valve, anterior side showing lunular incision (B1), inner shell surface (B2), outer shell surface (B3). C. NMNS PM 28189, articulated specimen, outer shell surface of right valve (C1), dorsal view showing the strong inflation (C2), anterior side showing lunular incision (C3).