Phylogenetic relationships within Cortinarius subgenus Myxacium, sections Defibulati and Myxacium

Abstract

Phylogenetic relationships of two sections from subgenus Myxacium in the brown-spored agaric genus Cortinarius were studied using nuclear DNA sequence data from the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene of 23 species of Cortinarius, including seven subgenera. Of these, ten species represent the focal study group from sections Defibulati and Myxacium, three species represent three additional sections within subgenus Myxacium, and ten species represent six remaining subgenera within Cortinarius. Phylogenies inferred using parsimony and maximum likelihood strongly supported the two sections as monophyletic, but did not support the subgenus Myxacium as a distinct lineage. Neither method of analysis resolved relationships below the sectional level. Morphological traits were examined for the two monophyletic groups traditionally classified as sections Defibulati and Myxacium. Absence of clamp connections is a synapomorphy of section Defibulati. Cladistic analyses confirm that members sampled from subgenus Myxacium in other sections are more closely allied with other subgenera, suggesting the current taxonomy needs revision to reflect phylogenetic relationships.

Key Words:

• Agaricales
• Basidiomycetes
• clamp connections
• ectomycorrhizal
• nuclear rDNA
• parsimony
• phylogeny