New Middle Miocene Mollusca from the Katsuta Group at Shinden, Tsuyama City, Okayama Prefecture, Southwest Japan. Part 1. Description of Perna oyamai sp. nov. and its Paleoecology

One interesting mytilid of the genus Perna is newly described from the middle Miocene Katsuta group at Shinden, Tsuyama City, Okayama Prefecture, Southwest Japan. The genus is the first record in Japan. This species, named Perna oyamai, may have clustered embedded in muddy substrate in the tidal to neritic zone and is considered to be one of representative indicators of tropical environmental conditions in the earliest middle Miocene of Japan.