Monochaetia is a pestalotiopsis-like genus characterized by 3–5-septate hyaline to brown conidia with single apical and basal appendages. Monochaetia species exhibit diverse conidial morphology, but many species lack molecular data and thus it is not clear if the genus is monophyletic. In this paper, combined LSU and ITS sequence data and morphological traits are used to introduce a new Monochaetia species, M. ilexae from Yunnan Province, China from dead leaves of Ilex species. Monochaetia ilexae shares similar morphology with the type, M. monochaeta and M. kansensis having fusiform conidia and has a similar range of conidia. However M. ilexae differs from M. monochaeta and M. kansensis having different conidia length, apical and basal appendage lengths. Phylogeny agrees with morphological differences allowing Monochaetia ilexae as a new species that clusters with Monochaetia species, but is separated from the main clade with high support.