SUMMARY
Six cultures of Microsporum amazonicum were recently isolated from the hair of six spiny rats (Proechimys guyannensis) trapped near the city of Belém, Brasil. When the six isolates were paired with each other in all possible combinations on soil-hair plates, eight of 15 pairs developed fertile ascocarps. Based on the morphology of the gymnothecia, the perfect state was classified in the genus Nannizzia. The perfect state was described and contrasted with the other species of Nannizzia.