Lithothelium japonicum (Lichenized Ascomycotina, Pyrenulaceae), a New Pyrenocarpous Lichen from Central Japan

Lithothelium japonicum Harada sp. nov. (lichenized Ascomycotina, Pyrenulaceae) is described from Chiba-ken, central Japan. It is characterized by a brownish green endophloeodic thallus, simple perithecia, non-gelatinized paraphyses with oil droplets, and 3-septate hyaline spores (10-14 X 4-5 ptm) with terminal lumina almost as large as the central ones. The genus Lithothelium is characterized by a crustose thallus having Trentepohlia as the phycobiont, perithecioid ascomata with lateral ostioles, almost simple paraphyses, asci with ocular chamber, and transversely-septate hyaline or brown ascospores with rounded lumina (Aptroot 1991a,b). The genus has about 20 species, mainly from the tropics, with records of three species in Asia: L. himalayense Upreti & Aptroot and L. obtectum (Muell. Arg.) Aptroot from India, and L. hyalosporum (Nyl.) Aptroot from the Maldives and New Guinea (Aptroot 1991b, Upreti & Aptroot 1996). There are no records of this genus from Japan; however, during my recent floristic survey in Chiba-ken, central Japan, a specimen was collected from the trunk of an old Castanopsis sieboldii in the precincts of a shrine that can be described as