A new species of Ancistrolepis (Gastropoda : Buccinidae) from the Iwaki Formation (lower Oligocene) of the Joban coal field, northern Japan

Abstract

Ancistrolepis (Ancistrolepis) iwakiensis sp. nov. from the lower Oligocene of the Joban coal field, northern Japan closely resembles both Ancistrolepis (A.) matchgarensis (Makiyama) from the upper Eocene to Oligocene of Sakhalin and Ancistrolepis (A.) rategiensis Titova from the upper Eocene of northwestern Kamchatka. A. (s.s.) iwakiensis sp. nov. documents an early evolutional history of Ancistrolepis (s.s.) that appeared in the northwestern Pacific during late Eocene time.