We encountered an unfamiliar ascomycete fruiting body, fitting characteristics of the genus Kretzschmaria, which features in a stipitate ascigerous stroma with carbonaceous interior and disintegrating perithecia. In this study, we report and characterize a new species of the decaying fungus. Compared to other species, one of the notable features of this specimen (TPML150908-046) is its stromatal size (up to 15 cm). Although TPML150908-046 is morphologically similar to K. milleri and K. sandvicensis, it differs sharply from both species in apical ring size (TPML150908-046, 6.5~10.5 µm; K. milleri, 11~16 µm) and ascospore width (TPML150908-046, 10.5~17 µm; K. sandvicensis, 8.5~11.5 µm). Phylogenetic trees based on β-tubulin, ITS, and RPB2 sequences showed that our collection clustered with K. sandvicensis, with the respective similarities for these sequences being 95.6%, 91.3%, and 97.7%, signifying it as another species. With these results, we report it as a new species, which we call Kretzschmaria quercicola sp. nov.
Keywords: Ascomycota; Kretzschmaria; Morphology; Phylogeny; Taxonomy.