A taxonomic re-evaluation of , a hyperparasitic synnematous hyphomycete on , with gen. et comb. nov. ().

About 70 y after the first report by Yosio Kobayasi, we collected a little-known synnematous hyphomycete, , on decaying basidiocarps of growing on dead culms of two bamboo species in Tateyama (on ), Chichibu (type locality of ; on ), and Shigakogen (on ) in Japan, and obtained isolates of both the parasite and its host. Kobayasi provided only brief Latin and Japanese descriptions and quite elementary illustrations for , without depositing any herbarium specimens including the holotype. In this paper, a lectotype and an epitype of this species are designated respectively from the original protolog (illustration) of Kobayasi and our new material collected in Chichibu. Phialidic conidiogenesis and 2- to 3-level verticillate conidiophores terminating in a whorl of 2-5 phialides were newly observed in this fungus on the natural substrate. ITS-LSU sequences of five isolates of collected in the three locations were identical. Phylogenetic analyses of these markers placed in , although other species of are classified in at present. A new genus for and a new combination, , are proposed here based on our morphological, ecological and phylogenetic data.