Inocybe section Rimosae in Utah: phylogenetic affinities and new species.

Results of a study on species of Inocybe section Rimosae sensu lato in Utah are presented. Eight species, seven from the Pseudosperma clade (section Rimosae sensu stricto) and one from the Inosperma clade (section Rimosae pro parte), are documented morphologically and phylogenetically. Five of the eight species, I. aestiva, I. breviterincarnata, I. cercocarpi, I. niveivelata and I. occidentalis-all members of the Pseudosperma clade-are described as new from Utah and other western states. Two European species, I. spuria and I. obsoleta, are confirmed from Utah. Inocybe aurora, originally described from Nova Scotia, is synonymized with I. obsoleta. The only member of the Inosperma clade recorded from Utah is I. lanatodisca, a widely distributed species for which three geographical clusters were detected. The phylogenetic analyses indicate that the Pseudosperma clade includes 53 clusters or species worldwide and that the Inosperma clade includes 47 such clusters. Many of these probably correspond to undescribed species. A key to species of section Rimosae sensu lato from Utah is provided together with illustrations of the eight species found in the state.