A Middle Permian Boreal-Tethyan mixed brachiopod fauna from Yakejima, southern Kitakami Mountains, NE Japan

A collection of brachiopods is described from the Middle Permian Oyakejima Formation of the Yakejima area, southern Kitakami Mountains, northeast Japan. This fauna consists of the following nine species: Waagenites soochowensis, Transennatia gratiosa, Kochiproductus sp., Compressoproductus compressus, Rhynchopora tchernyshae, Stenoscisma margaritovi, Martinia sp., Spiriferella cf. lita and Cleiothyridina subexpansa. The Yakejima fauna, including a before-described species Leptodus sp., is characterized by the mixture of the Boreal-type genera, Kochiproductus, Stenoscisma and Spiriferella, and the Tethyan-type genera, Transennatia, Compressoproductus and Leptodus. The occurrence of the Middle Permian Boreal-Tethyan mixed brachiopod fauna from the southern Kitakami Mountains provides evidence that this region was placed on the transitional zone between the Boreal and Tethyan Realms, nearby the Sino-Korean block, in the Middle Permian time