Pseudodidymella fagi gen. et sp. nov. and its hyphomycete anamorph Pycnopleiospora fagi gen. et sp. nov. on Fagus crenata in Japan

An unusual fungus was noted on Fagus crenata leaves in the mountainous region of Aomori Prefecture. It is characterized by a conidial mass that is being disseminated as a unit and infects leaves of F. crenata. The conidial mass is composed of many obclavate, phragmosporous conidia that are densely joined in fascicles. Each conidium consists of a body of several swollen cells, with narrow cylindrical fragments at the base and the apex. Each conidium can disarticulate into several individual cells in the middle, and narrow cylindrical fragments at the base and the apex. The teleomorph of the fungus was found on both artificially and naturally overwintered diseased leaves and is described as Pseudodidymella fagi, a new genus and species in the Phaeosphaeriaceae. The anamorph of the fungus is described as Pycnopleiospora fagi, a new genus and species of anamorph fungi. The teleomorph-anamorph connection was confirmed by inoculation and culture experiments.