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Abstract.- Taxonomic circumscription and segregation of the genus Lepiotahas 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 sensu stricto, Cystolepiota, Leucocoprinus, Leucoagaricus, Macrolepiota, Chlorophyllum, Cystoderma,and Ripartitella (Agaricaceae, Agaricales, Basidiomycotina). 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 RNA) 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. Parsimony analyses indicate Lepiota sensu lato includes both Agaricus and Coprinus section Comati, although lepiotoid segregate genera remain poorly resolved using this molecule. The support for Coprinus section Comati to be within the Agaricaceae presents interesting taxonomic problems involving nomenclatural precedence and usage of commonly known groups including Agaricus, Coprinus,and Lepiota.[Key Words: Agaricaceae, attine fungi, Coprinus, Lepiotaceae, 28S rDNA] |
Figure 1: Global analysis using several outgroups to determine the root of Lepiota sensu lato. One of 126 equally most parsimonious trees depicted as a phylogram showing relative branch lengths (tree length 640, CI = 0.398, RC = 0.208). Russula was used to orient the network. Bootstrap values greater than 50% are noted above the respective branches. The node between Lepiota sensu lato(Agaricaceae) and more distant outgroups is indicated (l). Taxa in parentheses indicate ant symbionts (G1 and G3 correspond to attine groups of Chapela et al., 1994).
Figure 2: A posteriori rooting
of Lepiota sensu latoand its closest allies using outgroups.
One of 421 equally most parsimonious trees depicted as a phylogram showing
relative branch lengths (tree length = 337, CI = 0.407, RC = 0.229).
Bootstrap values greater than 50% are noted above the respective branches.
Taxa in parentheses indicate ant symbionts (G1 and G3 correspond to attine
groups of Chapela et al., 1994).
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