A new species of Acanthothecis (Ostropales), highlights subtropical floristic elements of the southern Appalachian lichen biota in eastern North America

Acanthothecis fontana is described as new to science based on material collected in the southern Appalachian Mountains of western North Carolina. It is most similar to A. paucispora, but differs in its smaller ascospores and apparent allopatric distribution. In addition to the description of the new species, a key is provided to the genus Acanthothecis, including the species of Fissurina with warted paraphyses, together with a tabular summary of information pertaining to ascospores and chemistry.