Distribution and phylogenetic analyses of the genus Auricularia in the southeast United States

A recent discovery of Auricularia fuscosuccinea in east Tennessee has led to a study of the diversity within the genus Auricularia in the southeast United States. Auricularia currently comprises 10-15 well-established species, and most are considered to have intercontinental to cosmopolitan distributions. Though most regional field guides treat only one or two species for the southeast USA, five species, A. fuscosuccinea, A. auricula-judae, A. mesenterica, A. polytricha, and A. delicata have been reported from the region. This study seeks to evaluate current species concepts using phylogenetic and morphological analysis in order to understand regional diversity as well as provide new reports of geographical distributions. Historical collections from the University of Tennessee Herbarium, as well as fresh material observed in the field, have been examined and sequenced at two loci, ITS and rpb2. Phylogenetic trees have been constructed using maximum likelihood analysis, and preliminary results show diverse clades in need of taxonomic revision. Variation within traditional taxonomic characters has made it evident that additional characters are required to reflect the genetic diversity in the group. To this end, a new taxonomic character, the schizomedullum, is discussed as an important character to distinguish a new species from the morphologically similar species A. delicata. In addition, a reticulate, merulioid hymenial surface can no longer be considered a character unique to A. delicata.