Phylogenetic systematics of Lepiota sensu lato based on nuclear large subunit rDNA evidence

Taxonomic circumscription and segregation of the genus Lepiota has been pro blematic. Phylogenetic relationships were investigated for lepiotoid and cl osely related taxa using DNA sequence data. Our analysis reflects a broad s ampling across eight segregate genera used by Singer: Lepiota s.s., Cystole piota, Leucocoprinus, Leucoagaricus, Macrolepiota, Chlorophyllum, Cystoderm a, and Ripartitella (Agaricaceae, Agaricales, Basidiomycota). Related fungi were evaluated from the dark-spored genera Agaricus and Coprinus and repre sentative secotioid and attine fungi, along with more distantly related fun gi. DNA sequences were compared for the 5' end region of the nuclear encode d large subunit ribosomal RNA gene (25-28S rDNA) from 55 ingroup and outgro up taxa. Results from parsimony analysis are consistent with the exclusion of the tribe Cystodermateae (Cystoderma and Ripartitella) from the family A garicaceae, and the retention of the tribes Lepioteae and Leucocoprineae. L epiotoid segregate genera remain poorly resolved using this molecule. Parsi mony 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 involv ing nomenclatural precedence and usage of commonly known groups including A garicus, Coprinus, and Lepiota.