Abstract
On the basis of extensive field investigation and a series of herbarium specimen identifications, we present and discuss the descriptions and distribution of 22 species of Ramalina found in the Hengduan Mountains of southwestern China. In this revisionary study, representatives of the Ramalina genus, including R. americana, R. confirmata, R. dendriscoides, R. obtusata, R. pacifica, R. pentecostii, R. peruviana, R. shinanoana, and R. subcomplanata are found for the first time in this area. In addition, R. holstii is reported for the first time China. Finally, a newly described species identified as Ramalina hengduanshanensis S. O. Oh & L. S. Wang is reported. It is characterized as growing from a narrow holdfast, solid, sparsely or richly and irregularly dichotomously branched, palmate and flattened lobes with distinctly dorsiventral appearance, surface rugose to reticulate, surface rugosely cracked, dense chondroid tissue, helmet shaped soralia at the tip. The species grows on rock and tree at the highest elevations in this area. Although very few lichen species belonging to the genus Ramalina have been collected above 4,000 m, this new species is found at this elevation. We present detailed morphological, anatomical, and chemical descriptions of this species along with molecular phylogenetic analysis of the internal transcribed spacer rDNA sequences.