Staurothele nemorum sp. nov. (Ascomycota: Verrucariaceae), with a revised key to North American Staurothele s. lat.

Staurothele nemorum is described as new to science from the southern Great Plains of central North America. The species is characterized by a thin, areolate, epilithic thallus, sessile perithecia, globose to oblong hymenial algal cells and 8-spored asci. Staurothele hymenogonia is restored to the North American flora, based on material from the south-western Great Plains. An updated key to North American members of Staurothele s. lat. is provided.