1) This paper presents 19 species of Mougeotia known to our country. Among these, 8 species are newly found in the writer's materials collected from various localities in Japan. Other 11 species previously recorded by the writer or other workers have been collected from new localities which are listed with all previous records in Japan.
2) Mougeotia austrica Czurda, M. globulispora Jao, M. gracillima (Hassall) Wittrock, M. lamellosa Jao, M. punctata Wittrock and M. rotundangulata Jao have been newly recorded in Japan.