Abstract
Asexual reproductive bodies, gemmae, were newly found on branches of Pterobryum arbuscula collected from Chichibu, Saitama Prefecture. The gemmae of P. arbuscula are clustered around the tip of branches and are ovoid to spindle-shaped, dark-green, smooth, 100-200μm long, 30-45μm thick and consisting of 10-20 cells with yellowish- or reddish-brown cell walls (Fig. 1). They are borne on filamentous, branched stalks. The size and number of the gemmae are variable. Terminal cells of the gemmae are usually thin-walled and obliquely walled, which suggests that the cell division occurred at the apical cell, not at the basal cell. Collections from several other localities in Japan were found to bear numerous gemmae. The presence of gemmae appears to be rather common in this species. Another species, Ptcrobryum subarbuscula Broth., is known in Japan from Yakushima Isl., of which. Noguchi (1937) described the gemmae whose character closely resembles that of P. arbuscula. Representative specimens in which gemmae were observed. Pterobryum arbuscula Mitt. Honshu. Saitama Pref., Chichibu-gun, Ohtaki-mura, 1700 m, Higuchi 10774 (HIRO). Hiroshima Pref., Jinseki-gun, Jinseki-cho, 400 m, Higuchi 5235 (HIRO). Shikoku. Tokushima Pref., Miyoshi-gun, Mt. Tsurugi, 1100 m, Higuchi 5425 (HIRO). Kyushu. Kumamoto Pref., Kikushi City, 550 m, Higuchi 10727 (HIRO). P. subarbuscula Broth. Formosa. Prov. Tainan, Mt. Kodama, Noguchi 5883 (NICH).
