Ascosphaera subglobosa, a new spore cyst fungus from North America associated with the solitary bee Megachile rotundata

Ascosphaera subglobosa (Eurotiomycetes: Onygenales) is newly described from the pollen provisions and nesting material of the solitary leaf-cutting bee Megachile rotundata in Canada and the western United States. This new species, related to A. atra and A. duoformis, is distinguished from other Ascosphaera species by its globose to subglobose ascospores, evanescent spore balls and unique nuclear ribosomal DNA sequences (ITS and LSU).