The phylogenetic relationship of the coelomycete genus Infundibulomyces with cupulate conidiomata was assessed by ribosomal DNA sequences of partial small subunit (SSU) and partial large subunit (LSU) regions using maximum parsimony and Bayesian analysis. The genus has no known teleomorph. A new species, Infundibulomyces oblongisporus, is described from collections on a senescent angiosperm leaf from Thailand based on morphological and phylogenetic evidence. Both Infundibulomyces species form a monophyletic group in the Chaetosphaeriaceae (Chaetosphaeriales, Sordariomycetidae) with Dictyochaeta simplex as a sister clade. Chaetosphaeriaceae with a coelomycete anamorph has not been reported previously.