A bitunicate ascomycete bearing brown 1-septate ascospores consistent with the botryosphaeriaceous genera Dothiorella and Spencermartinsia was observed on discarded grapevine (Vitis vinifera L.) canes, and in culture was purported to yield a coelomycetous asexual morph in Spencermartinsia. However, morphological studies and amplification and sequencing of the internal transcribed spacer (ITS) region and portions of the small (18S) and large (28S) subunits of the nuclear ribosomal RNA gene identified the ascomycete as Munkovalsaria donacina (Niessl) Aptroot, and revealed that the fungus is neither connected to an asexual morph in Spencermartinsia, nor related to the Botryosphaeriaceae (Botryosphaeriales). Instead, these findings provide the first report of M. donacina from grapevines and Desert Ash (Fraxinus angustifolia subsp. angustifolia Vahl), extending the range of the taxon to 38 species in 24 families.