A fungus isolated from Norway maple (Acer platanoides) in the Boston, Massachusetts, area was determined to be a species of Glomerella, the teleomorph of Colletotrin chum acutatum. Pure cultures of the fungus were obtained from discharged ascospores from perithecia in leaf tissue. This fungus was determined to be homothallic based on the observation of perithecial development in cultures of single-spore isolates grown on minimal salts media and with sterile toothpicks. A morphological and molecular analysis was conducted to determine the taxonomic position of this fungus. Parsimony analyses of a combined nucleotide dataset of the ITS and LSU rDNA region, and of the D1-D2 LSU rDNA region, indicated that this species has phylogenetic affinities with Colletotrichum acutatum, C. acutatum f. sp. pineum, C. lupini, C. phormii and G. miyabeana. These results are significant because C. acutatum has not been reported on Acer platanoides. In addition the consistent presence of perithecia on leaf tissue and in culture is unusual for Colletotrichum, suggesting that the teleomorphic state is important in the life cycle of this fungus.