Occurrence of Epilucina californica (Conrad) (Bivalvia: Lucinidae) from the Neogene of Japan, with notes on the biogeographic history of Epilucina

Abstract

ABSTRACT The California lucine, Epilucina californica (Conrad, 1837), is reported from lower Middle Miocene to Upper Pliocene strata in Japan. This extends the oldest record of this species and represents the first detailed record of the species and genus in the western North Pacific region. Based on the Paleogene fossil record of Epilucina and the general migration pattern of Neogene North Pacific mollusks, it is inferred that E. californica originated in the eastern North Pacific during Late Oligocene or Early Miocene time and migrated westward to the western North Pacific during the early Middle Miocene. The western North Pacific populations of E. californica became extinct by the end of the Pliocene, whereas the eastern North Pacific populations survive in California. This species is, therefore, regarded as a northeastern Pacific restriction taxon. Two Japanese fossil species, Lucina (Myrtea) nipponica Nomura and Hatai, 1936 and Lucina japonica Ozaki, 1958 are junior synonyms of E. californica.