Abstract
Eighty-five fossil and Recent species of the genus Loxoconcha (Crustacea : Ostracoda) from East Asia are systematically reexamined. On the basis of carapace morphology, the genus Loxoconcha from East Asia is divided into five species groups : L. pulchra, L. optima, L. japonica, L. uranouchiensis and L. japonica species groups. The migration and speciation patterns of four species of the L. japonica species group are as follows. In Late Miocene, L. lilljeborgii and L. tumulosa were distributed over the Paleo-Indian Ocean. In Early Pliocene time, these species migrated to the Western Pacific and L. japonica evolved from populations of L. tumulosa by peramorphic evolution. In the Middle Pleistocene, L. shanhaiensis evolved from populations of L. japonica in the Ryukyu Islands by paedomorphic evolution.
