A New Subspecies, Entemnotrochus rumphii kushimotoensis, (Gastropoda: Pleurotomariidae) from the Middle Miocene of Wakayama Prefecture, Central Japan

Abstract

A new subspecies of Entemnotrochus rumphii (Schepman, 1879) from the middle Miocene Shikiya Formation, Kumano Group, at Uematsu, Kushimoto-cho, Higashimuro-gun, Wakayama Prefecture, central Japan is described herein as E. rumphii kushimotoensis n. subsp. This new subspecies is distinguished from E. rumphii rumphii by having a lower spire, a selenizone situated below mid-whorl and a larger number of spiral cords above the selenizone. Judging from the geographical distribution and the morphological affinities of the living E. rumphii rumphii, the new subspecies seems to be an ancestral form of the Recent species.