Phylogenetic taxonomy of the Inocybe splendens group and evolution of supersection "Marginatae"

A phylogenetic and taxonomic study of the Inocybe splendens complex in western North America is presented. Our analysis indicates that western North American and European specimens referable to I. splendens sensu lato cluster into eight clades and that European and western North American representatives of this taxon are not conspecific. Section Splendentes and supersection "Marginatae" of Inocybe, smooth-spored taxa characterized by a syndrome of unique developmental characters (entirely or mostly pruinose stipe, absence of cortina, frequent presence of marginate basal bulb) are not monophyletic. The species concept for I. splendens is discussed, and a lectotype for I. splendens sensu Heim is designated. Two new species, I. monticola and I. praecox, are illustrated and described. The poorly known species I. bakeri is redescribed from type material, and a key for 22 species is provided for identification of these and other non-reddening species with smooth spores and a caulocystidiate stipe reported from North America and Europe.