During taxonomic and phylogenetic studies of fungi on pteridophytes in Thailand, Monilochaetes pteridophytophila sp. nov. was collected from the frond stalks of a tree fern (Alsophila costularis, Cyatheaceae). The new species is introduced, based on evidence from morphology and phylogenetic analyses of a concatenated dataset of LSU, ITS, SSU and RPB2 sequences. Monilochaetes pteridophytophila differs from extant species of Monilochaetes in having darker conidiophores with fewer septae (1–4-septate). Monilochaetes pteridophytophila forms a distinct clade, basal from other species of Monilochaetes in Australiascaceae. A detailed description and illustrations of the new species are provided. We also provided a synopsis of accepted species of Monilochaetes.