A revision of Hypotrachyna subgenus Parmelinopsis (Parmeliaceae) in eastern North America

A taxonomic revision of the Hypotrachyna subgenus Parmelinopsis in eastern North America is presented based on molecular phylogenetic analyses of ITS and mtSSU data, extensive field observation and analyses of chemical and morphological data. Each species is described, illustrated with photographs, and the distribution in the region is mapped. An identification key is also presented. Eleven species are recognized: H. afrorevoluta, H. appalachensis, H. britannica, H. cryptochlora, H. horrescens, H. kauffmaniana, H. minarum, H. mcmulliniana, H. revoluta, H. showmanii and H. spumosa. Extensive discussion of prior studies is provided, particularly with respect to the delimitation of H. afrorevoluta and H. revoluta. Hypotrachyna kauffmaniana is described from the central and southern Appalachian Mountains and separated from H. afrorevoluta and H. revoluta by its ascending secondary lobes and pustulose soralia that are primarily confined to the secondary lobes. Hypotrachyna horrescens is shown to correspond to a taxon with narrow lobed, small thalli with ciliate isidia. Hypotrachyna mcmulliniana is described from material collected throughout southeastern North America that is chemically identical to H. horrescens but differs in having larger thalli and sparsely ciliate isidia. Hypotrachyna appalachensis is described to accommodate material previously referred to H. minarum but that differs in the production of 4,5-di-O-methylhiascic acid in high concentrations (vs. absent or present as a trace in H. minarum). Hypotrachyna britannica is reported for the first time from North America.