ABSTRACT Buellia sharpiana is described as new to science based on material from a single locality at the summit of Mt. LeConte in Great Smoky Mountains National Park in the southern Appalachian Mountains of eastern North America. The species is characterized by its ascospore size, thallus morphology, medullary I reaction, and the production of xanthones. Comparison is made to two morphologically similar species, B. ocellata (Flo¨ rke ex Flot.) Ko¨ rb. and B. jugorum (Arnold) Arnold.