During a survey of freshwater fungi in temperate southern Australia, two previously unknown anamorphic ascomycetes were found. The coelomycetous ascomycete was placed in the family Morosphaeriaceae (Pleosporales) as a new genus based on molecular data. We introduce the new genus and species Microvesuvius unicellularis with morphological and molecular data. The Dictyochaeta-like hyphomycete was placed in Achrochaetabased on both morphological characters and phylogenetic analyses using ITS, 28S, and tef1 sequences. Achrochaeta rivulata is the second species described within this genus.