Phylogenetic systematics of Lepiota sensu lato based on nuclear large subunit rDNA evidence
Taxonomic circumscription and segregation of the genus Lepiota has been problematic. Phylogenetic relationships were investigated for lepiotoid and closely related taxa using DNA sequence data. Our analysis reflects a broad sampling across eight segregate genera used by Singer: Lepiota s:s., Cystolepiota, Leucocoprinus, Leucoagaricus, Macrolepiota, Chlorophyllum, Cystoderma, and Ripartitella (Agaricaceae, Agaricales, Basidiomycota). Related fungi were evaluated from the dark-spored genera Agaricus and Coprinus and representative secotioid and attine fungi, along with more distantly related fungi. DNA sequences were compared for the 5' end region of the nuclear encoded large subunit ribosomal RNA gene (25-28S rDNA) from 55 ingroup and outgroup taxa. Results from parsimony analysis are consistent with the exclusion of the tribe Cystodermateae (Cystoderma and Ripartitella) from the family Agaricaceae, and the retention of the tribes Lepioteae and Leucocoprineae. Lepiotoid segregate genera remain poorly resolved using this molecule. Parsimony analysis indicates that both Agaricus and Coprinus section Comati are nested within the lepiotoid fungi. The support for Coprinus section Comati to be within the Agaricaceae presents interesting taxonomic problems involving nomeclatural precedence and usage of commonly known groups including Agaricus, Coprinus, and Lepiota.
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