Phaeoisaria is a dematiaceous hyphomycete genus with species producing indeterminate synnemata with septate or nonseptate ellipsoidal, obovoidal, fusiform-cylindrical or falcate conidia formed on a sympodially extending rachis, occurring on decaying wood, plant debris or soil sediments (e.g. Sutton 1973, Deighton 1974, Castañeda et al. 2002, Seifert et al. 2011, Mel’nik 2012, Cheng et al. 2014, Crous et al. 2015). The genus was proposed by Von Höhnel (1909) with the only species Ph. bambusae. It was originally described as an asexual state of Neopeckia bambusae, inferred from the intimate juxtaposition of synnemata and ascomata. Based on his revision of type and herbarium material, Deighton (1974) considered Ph. bambusae a synonym of Ph. clematidis. He compiled an extensive synonymy of the latter species, distinguishing it from morphologically similar Ph. magnifica, which has broader conidia. Deighton’s concept of Ph. clematidis seems to represent a complex of several phylogenetic species. Phaeoisaria now includes 19 species, five of which were analysed in our study. The sampled species form a strongly supported monophyletic clade in the Pleurotheciales that includes species with synnemata and conidiophores formed in fascicles.