Systematics of the genus Auricularia with an emphasis on species from the southeastern United States.

Abstract

The genus Auricularia comprises 10-15 recognized species worldwide, and most are considered to have intercontinental to cosmopolitan distributions. Though regional field guides for the southeastern United States treat only one or two species, five species, A. fuscosuccinea, A. auricula-judae, A. mesenterica, A. polytricha, and A. delicata, have been recorded from the region. This study seeks to evaluate and revise current species concepts in Auricularia using phylogenetic and morphological methods to better understand the species occurring in the southeastern United States. Historical collections from herbaria and fresh material from the field have been examined and sequenced at two loci, ITS and rpb2. Phylogenetic results indicate several diverse clades are in need of taxonomic revision. Previous reports of A. auricula-judae in the southeastern U.S. likely represent a clade of A. americana. Collections identified as A. delicata are found to be polyphyletic and distributed in four clades. Variation in the presence or absence of a medulla layer in some species, previously a key morphological character, has made it evident that additional characters are required to reflect the genetic diversity in the genus. A

Auricularia thailandica sp. nov. (Auriculariaceae, Auriculariales) a widely distributed species from Southeastern Asia

“…ITS analysis has separated A. auricula-judae, A. polytricha and A. fuscosuccinea into three well-supported clades (Montoya-Alvarez et al, 2011). Further analyses of ITS with a large sample size revealed nine species of Auricularia with relevant morphological and ecological characters (Looney et al, 2013). In addition, the analysis of rpb2 showed similar groupings as the ITS sequence results, but with a higher bootstrap support (Looney et al, 2013).…”

“…In the ITS phylogeny all the specimens from different geographic locations group in a monophyletic clade and A. thailandica is a distinct species with high bootstrap support. In the present study we used both morphological and molecular data to define A. thailandica as a distinct species (Looney et al, 2013;Malysheva & Bulakh, 2014;Wu et al, 2014b).…”

“…fuscosuccinea, A. minor, A. scissa and A. subglabra (Table 2). The abhymenial hairs of A. fuscosuccinea and A. scissa are gregarious and tufted (Looney et al, 2013). Although A. minor is characterized by short abhymenial hairs the basidiomata are smaller (less than 2 cm) (Malysheva & Bulakh, 2014) than A. thailandica.…”

“…A. fibrillifera is distinct from A. thailandica in having thick-walled, acute, free or partly fasciculate hairs and thinner zones (Kobayashi, 1981). A. subglabra has solitary, infrequent hairs (Looney et al, 2013). A. subglabra is distinguished from A. thailandica by the lack of abhymenial hairs, with only a few short hairs present at irregular intervals throughout the zona pilosa.…”

“…Fifteen species and five variants of Auricularia were monographed by Kobayashi (1981). A recent study estimated that this genus comprises 10-15 species throughout the world (Looney et al, 2013), while Kirk et al (2008) estimated there are eight species worldwide.…”