Taxonomy and Phylogeny of Cystolepiota (Agaricaceae, Agaricales): New Species, New Combinations and Notes on the C. seminuda Complex

Species of Cystolepiota are known as diminutive lepiotaceous fungi with a worldwide distribution. Previous studies revealed that Cystolepiota is not monophyletic and preliminary DNA sequence data from recent collections suggested that several new species exist. Based on multi-locus DNA sequence data (the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2, ITS; the D1–D2 domains of nuc 28S rDNA, LSU; the most variable region of the second-largest subunit of RNA polymerase II, rpb2 and a portion of the translation–elongation factor 1-α. tef1), C. sect. Pulverolepiota forms a distinct clade separating from Cystolepiota. Therefore, the genus Pulverolepiota was resurrected and two combinations, P. oliveirae and P. petasiformis were proposed. With the integration of morphological characteristics, multi-locus phylogeny, and information on geography and habitat, two new species, viz. C. pseudoseminuda and C. pyramidosquamulosa, are described and C. seminuda was revealed to be a species complex containing at least three species, viz. C. seminuda, C. pseudoseminuda, and Melanophyllum eryei. In addition, C. seminuda was re-circumscribed and neo-typified based on recent collections.