Thelenella luridella (Nyl.) Mayrh. is reported as new for Japan, as the first member of this genus. It was found on seaside rocks in the splash zone in Miyagi-ken, northern Honshu, and on Haha-jima Island of the Ogasawara Islands. It has been previously known mainly from the tropics and subtropics in the world, and this is the first record in eastern Asia. A description and figures are provided for T. luridella on the basis of the Japanese materials. lichens, lichenized Ascomycota, Thelenellaceae, Thelenella luridella, taxonomy, distribution, Japan, Ogasawara Islands, saxicolous, maritime