Cortinarius atropileatus sp. nov. (Cortinariaceae) from New Zealand

Cortinarius is a taxonomically diverse genus of ectomycorrhizal fungi. It has a global distribution and is the dominant genus found under Nothofagus in New Zealand. Here we describe Cortinarius atropileatus, associated with Nothofagus. The new species is morphologically very similar to C. dulciolens but may be distinguished by the vivid mauve-violet lamellae when young, spores with reduced verrucose ornamentation and a less pronounced plage, and the presence of abundant clamp connections in the epicuticular hyphae. A molecular phylogenetic analysis of the internal transcribed spacer (ITS) region and RNA polymerase second largest subunit (RPB2) shows that C. atropileatus is in C. sect. Dulciolentes ined. and is sister to an undescribed sequestrate species.