A new septate gregarine, Hyalospora japonica, is described from the intestine of a Japanese Thysanuran Pedetontus nipponicus. This is the first report on the genus Hyalospora from Japan. The new species is related to H. roscoviana, but it differs from the latter in the size of gamont, the shape of oocyst, the color of endoplasm of young gamont and the host.
