Taxonomy of Buelliaepigaea -group (Caliciales, Caliciaceae), revealing a new species and two new records from China.

During the Second Tibetan Plateau Scientific Expedition and Research Program, we discovered that white terricolous lichenized fungal species of Buellia De Not. were widely distributed across the Tibetan Plateau. After examining their morphology, chemistry and phylogeny, we describe Buelliaalpina Xin Y. Wang & Li S. Wang, sp. nov. as new to science. It is present in alpine meadows, and is characterized by its effigurate thallus, distinct linear marginal lobes, cover of thick white pruina and four-spored asci. This is also the first report of Buelliaelegans Poelt and Buelliaepigaea (Pers.) Tuck from China. The Buelliaepigaea -group has previously been characterized by white and often effigurate thalli that occur mainly on soil. However, our results show that species in this group actually belong to two distinct clades. This conclusion is based on analyses of the nuITS region and the combined regions dataset (nuITS-nuLSU-mtSSU-β-tubulin). We discuss differences in morphology, anatomy, chemistry and ecology among the putative Buelliaepigaea -group. Detailed descriptions and figures for the three species from China and a key for species of Buelliaepigaea -group are provided.