Japanese species of the genus Oyamia (Plecoptera: Perlidae), with notes on O. nigribasis from Korea

A new species of Oyamia. O. cryptomeria, is described from western Honshu, Japan. The other two Japanese species, Oyamia lugubris (McLachlan) and O. seminigra (Klapalek), are redescribed. The new species is distinguished from the other species of Oyamia by the male genitalia and punctures oil the egg. The O. seminigra complex is proposed for the new species and O. seminigra. The two species in the complex and the other Japanese species, O. lugubris, share some characteristics, of larvae and male genitalia, An only single representative of the genus from the continent, O. nigribasis Banks, has different characteristics from the Japanese species. An additional characteristic of the genus is a feature of the mouthparts; i.e. a row of setae on the inner side of the larval lacinia.