Data from: Studies in Lichens and Lichenicolous Fungi – no. 18: resolution of three names introduced by Degelius and Magnusson based on material from the Great Smoky Mountains

Arthonia biseptata is shown to be a species of Mycoporum, likely narrowly
endemic to high elevations of the southern Appalachian Mountains and the
new combination M. biseptatum is proposed. Lecidea degelii is shown to
apply to the sorediate morphotype of Porpidia albocaerulescens. The
results of molecular phylogenetic analyses of nrITS and mtSSU sequence
data of sorediate and esorediate populations of P. albocaerulescens are
presented. These analyses recovered the sorediate and esorediate
morophotypes together in a single clade as strongly-supported monophyletic
entities. As a result the new combination Porpidia degelii is proposed,
the species illustrated, and the North American distribution of P. degelii
with respect to P. albocaerulescens is discussed. These data strongly
refute the notion that “species pairs” do not exist in Porpidia. Lecidea
subtilis is placed in synonymy with Pyrrhospora varians.