Biogeography of the genus Neptunea (Gastropoda : Buccinidae) from the Pliocene and the lower Pleistocene of the Japan Sea borderland

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Fourteen species of Neptunea are listed from the Pliocene and lower Pleistocene of the Japan Sea borderland. Among them, Neptunea (Neptunea) eos (Kuroda), N. (N.) hataii Noda, and N. (Golikovia) nikkoensis Nomura are extinct. These species and a part of the N. polycostata stock in the Japan Sea suffered extinction before the end of the early Pleistocene. However, the N. polycostata stock survived in the Okhotsk and Bering Seas. On the other hand, N. intersculpta (Sowerby) and N. (Barbitonia) arthritica (Bernardi) are still living in the Japan Sea. This contrast is due to the Plio-Pleistocene records on the Pacific side and eurythermal ecology of N. intersculpta and N. arthritica.