Cortinarius, subgenus Telamonia, section Disjungendi, cryptic species in North America and Europe

Cortinarius disjungendus and morphologically similar species were studied using ITS sequences of nine type collections and 18 specimens in the study group, as well as 13 sequences from public sequence repositories, including sequences of three type specimens. In addition, previously published rpb2 sequences were used to provide the phylogenetic position of species in the subgenus Telamonia. Based on these results, the new section Disjungendi, subgenus Telamonia, is proposed. Six species belong to this section: C. claroplaniusculus, C. disjungendus, C. disjungendulus, C. olididisjungendus, C. orasericeus, and C. piceidisjungendus. Of these, C. disjungendus, C. disjungendulus, and C. claroplaniusculus are to date only known from Europe, whereas the others occur both in North America and Europe. Based on ITS sequences, three of the six species had taxonomic synonyms: C. claroplaniusculus (synonym C. hymenoluctus and C. planodepressus), C. disjungendus (synonyms C. remauxii, C. conicosordescens, and C. solivagus), and C. orasericeus (synonym C. brunneofulvus f. myrtillophilus). This study demonstrates how difficult it can be to identify species only on the basis of morphology, and emphasizes the importance of molecular studies of type and of other specimens, particularly in groups with cryptic taxa.