Abstract
The ostracod genus Aurila is distributed worldwide in shallow marine areas, and fossils of this genus are commonly found in the Late Cenozoic strata of Japan. We describe a new species of Aurila, A. tsukawakii, from the coast of the Sea of Japan in the Lower Pleistocene Omma Formation, Toyama Prefecture, central Japan. Its geological and geographical occurrence suggests that this species originated in the Late Pliocene within the semi-closed Sea of Japan around 3 Ma as an endemic species and likely went extinct by the Middle Pleistocene (ca. 0.4 Ma) at the latest. Another related species of Aurila, Aurila sp., appeared in the Sea of Japan during the Late Pleistocene (ca. 0.1 Ma) at the latest, and continues to inhabit the Sea of Japan along the Japanese coast today. We briefly discuss the ecology, biogeography, and distributional pattern of normal pores in the median area of the carapace of these two species.
