Remototrachyna, a newly recognized tropical lineage of lichens in the Hypotrachyna clade (Parmeliaceae, Ascomycota), originated in the Indian subcontinent.

Biogeographical studies of lichens used to be complicated because of the large distribution ranges of many species. Molecular systematics has revitalized lichen biogeography by improving species delimitation and providing better information about species range limitations. This study focuses on the major clade of tropical parmelioid lichens, which share a chemical feature, the presence of isolichenan in the cell wall, and a morphological feature, microscopic pores in the uppermost layer. Our previous phylogenetic studies revealed that the largest genus in this clade, Hypotrachyna, is polyphyletic with a clade mainly distributed in South and East Asia clustering distant from the core of the genus. To divide the Hypotrachyna clade into monophyletic groups and to reevaluate morphological and chemical characters in a phylogenetic context, we sampled ITS, nuclear large subunit (nuLSU) and mitochondrial small subunit (mtSSU) rDNA sequences from 77 species. We are erecting the new genus Remototrachyna for a core group of 15 former Hypotrachyna species. The segregation of Remototrachyna from Hypotrachyna receives support from morphological and chemical data, as well from maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses of the DNA. We used a likelihood approach to study the geographic range evolution of Remototrachyna and Bulbothrix, which are sister groups. This analysis suggests that the ancestral range of Remototrachyna was restricted to India and that subsequent long-distance dispersal is responsible for the pantropical occurrence of two species of Remototrachyna.