Abstract

Ten new species of Cortinarius are described from Costa Rican neotropical montane forests based on morphological and molecular phylogenetic data. Morphological features of the basidiomes and nuclear rDNA sequence analyses place these species in the following clades: Anomali (Cortinarius sericeolazulinus), Cotoneus (Cortinarius aureopigmentatus), Limonii (Cortinarius aurantiobrunneus), Lustrati (Cortinarius comarostaphylii, Cortinarius comparioides, Cortinarius ovreboi), Myxacium (Cortinarius costaricensis), and Telamonia (Cortinarius carranzae, Cortinarius quercoarmillatus, Cortinarius savegrensis). Species delimitations, diagnostic characters, sequence pair wise comparisons, and affinities to closely related species are included for each species. These Cortinarii occur with several species of Quercus with the exception of C. comarostaphylii, which is associated with Comarostaphylii (Ericaceae) in the paramo and in mixed forests with Quercus and Comarostaphylis.