Molecular phylogeny of onygenalean fungi based on small subunit ribosomal DNA (SSU rDNA) sequences

Abstract

Phylogenetic analysis of nucleotide data from small subunit ribosomal DNA (SSU rDNA) sequences (ca. 1685 bp.) was performed on 19 taxa of the Onygenales and three related mitosporic fungi. Phylogenetic trees were constructed by the neighbor-joining method with the sequence data of related taxa obtained from DNA databases. The species in the Onygenales form two clusters and seven subclusters, and the tree topology reflects the traditional classification by Currah (1985) with some exceptions. The Myxotrichaceae is placed in the different lineage, separate from other plectomycetous taxa and among the Leotiales and the Erysiphales. Furthermore, two separate lineages in the Myxotrichaceae were found. Tree topology suggested the Onygenaceae is polyphyletic and composed of three subgroups; 1) most members of Onygenaceae, 2) Spiromastix warcupii, and 3) pathogenic dimorphic fungi classified in Ajellomyces.