A new revision of the lichen genus Pleopsidium (Acarosporales, Acarosporaceae) in China reveals two new species.

Based on a combination of morphological, chemical, and phylogenetic analyses, we present a new revision of the lichen genus Pleopsidium in China. Pleopsidiumtumidulum sp. nov. and P.corrugatulum sp. nov. are proposed as new species to science, both included in a distinctive clade (clade 1) together with P.gobiense. These three species are characterized by the absence of fatty acids, acaranoic and acarenoic acids, and share similar ecological traits. In contrast, species containing fatty acids, including Pleopsidiumflavum, P.chlorophanum, and P.discurrens, constitute a separate clade (clade 2). Fresh specimens of Pleopsidiumdiscurrens were collected from the type locality, Yulong Snow Mountain, and molecular data were generated to confirm the phylogenetic position of the species. Our study additionally reveals substantial morphological variation in this species. New collections and sequences of Pleopsidiumgobiense from Hami City, the type locality, are provided, from which a neotype is designated, confirming its phylogenetic position. Differences in morphology, anatomy, chemistry, and ecology among Pleopsidium species from China are discussed. A key and several phylograms are provided.