Cosmospora is a genus of ascomycete fungi in the family Nectriaceae. The genus, as circumscribed by Rossman et al. (1998), included all the nectrioid species with small, reddish, non-ornamented sexual fruiting bodies that collapse laterally when dry. However, the genus was shown to be polyphyletic, and the majority of species were re-classified into revived or recently established genera that are monophyletic. Cosmospora sensu Rossman housed members of the following genera: Chaetopsina, Cylindrocladiella, Fusicolla, Macroconia, Mariannaea, Microcera, Pseudocosmospora, Stylonectria, and Volutella. Cosmospora was restricted to species having acremonium-like asexual morphs that grow on polypores and xylariaceous fungi.