Pronectria japonica growing on an unidentified Ochrolechia species is described as new to science. Dactylospora glaucomarioides, D. cf. pertusariicola, Lichenodiplis anomala, L. ochrolechiae, and Sagediopsis campsteriana are newly reported for Japan. Pyrenidium actinellum s. l. is for the first time documented on Ochrolechia. A key to the known species of lichenicolous fungi and lichens growing on Ochrolechia is presented. Key words: Japan, lichen parasites, Bionectriaceae, Hypocreales.