Praecaprotina kashimae nov sp.(Bivalvia, Hippuritacea) from the Daiichi-Kashima Seamount (Japan Trench)

摘要

Praecaprotina kashimae nov. sp. is described from the Daiichi-Kashima Seamount in the Japanese group of guyots. This species differs in size, radial bands, longitudinal ornamentation, and some internal characters from the Japanese Praecaprotina yaegashii. Associated microfossils, mainly Orbitolinidae, point to the late Aptian-Albian p.p., whereas the associated requieniid rudist Kugleria sp. merely reflects an Albian age. Our finding illustrates the biogeographic affinity of the Daiichi-Kashima fauna with that of Japan and tends to support a "Japanese Province," with Praecaprotina as index taxa, The latitudinal extent and configuration of the Japanese province in the Western Pacific during the late Aptian-Albian depends on palaeotectonic reconstructions dealing with the original geographic position of the Daiichi-Kashima Guyot.