The faces of Bacidia schweinitzii: molecular and morphological data reveal three new species including a widespread sorediate morph

Bacidia schweinitzii is a common crustose lichen that is widespread in eastern North America. It is comprised of three distinct morphotypes differing in apothecial pigmentation. Here we show that molecular data from the mtSSU region affirms the distinctiveness of these morphotypes, prompting the recognition of three species: B. schweinitzii s.str., B. ekmaniana sp. nov. and B. purpurans sp. nov. We also show that a common sorediate crustose lichen, sympatric with B. schweinitzii, represents a monophyletic lineage whose relationship with B. schweinitzii s.str. could not be resolved with certainty using analyses of ITS and mtSSU sequence data. We recognize this sorediate lineage as a distinct species, B. sorediata sp. nov. All four taxa are described, illustrated and mapped.