Cortinarius phylogeny and possible taxonomic implications of ITS rDNA sequences

Internal transcribed spacer (ITS) nuclear ribosomal DNA (rDNA) sequences of 2'7 species of Cortinarius representing the subgenera Cortinarius, Dermocybe, Leprocybe, Myxacium, Phlegmacium, Sericeocybe, and Telamonia were studied and compared with ITS rDNA of Rozites caperatus and three outgroup taxa: Gymnopilus sapineus, Hypholoma capnoides, and Tricholoma equestre. With two different gap treatments, the sequence data were used to reconstruct the phylogeny of Cortinarius using maximum parsimony (PAUP). Alternative outlines of the subgenera compiled from literature were used to create phylogenetic constraints which were subjected to parsimony analysis using the ITS data. Unconstrained and constrained parsimony trees were compared using a maximum likelihood method (DNAML/PHYLIP). In the ITS based phylogenies Cortinarius s. l. was consistently divided into two lineages, one centered around the members of the subgenus Telamonia, the other comprising the majority of ingroup taxa including Rozites. Because additional data are needed before nomenclatorial changes are considered, we present an outline of what may be regarded as two separate genera, Cortinarius s. s. and "Telamonia." The status of Rozites will depend on similar future studies.