Global diversity and taxonomy of the Auricularia auricula-judae complex (Auriculariales, Basidiomycota)
Auricularia auricula-judae was previously considered a single species, but was recently demonstrated to be a species complex. The economically important, cultivated Auricularia mushrooms are included in the complex. Two species are cultivated, but have been treated as a single species: A. auricula-judae. Fifty samples of so-called A. auricula-judae from Asia, Europe, and North America were analyzed using morphology and molecular phylogeny. Phylogenetic analyses were carried out by ITS sequence and combined ITS, LSU, and rpb2 sequence, and 16 ITS, 16 LSU, and 16 rpb2 sequences were newly generated. Seven species in the complex were delineated, including three species new to science: Auricularia angiospermarum, A. minutissima, and A. tibetica. Illustrated description of the three new species and discussions in relation to other species are introduced in this paper. Auricularia heimuer is the most extensively cultivated species of Auricularia. Auricularia villosula is also cultivated, but has been named by the mushroom production industry A. heimuer. The size of basidiospores and presence or absence of medulla are important characters for differentiating the species within the complex, and ITS sequence data is a sensitive marker to discriminate species. A synoptic table of comparison of species in the complex is provided including the most important characters of the seven species.