Cortinarius species diversity in British Columbia and molecular phylogenetic comparison with European specimen sequences

Abstract

Throughout the world, the diversity of fungi remains poorly characterized and Cortinarius is a classical example of a difficult, species-rich, and under-researched mushroom genus. Here, we sequenced and analyzed ribosomal internal transcribed spacer (ITS) sequence barcodes from herbarium specimens to improve understanding of Cortinarius species diversity in British Columbia (B.C.), Canada. Starting with 962 specimen sequences, 617 from B.C. herbaria, we present a maximum likelihood tree showing 179 putative Cortinarius species in British Columbia. As a working definition, we considered a “species” to be a monophyletic clade that included a reliably identified reference sequence, with a maximum of 3% ITS sequence variation. If no reference sequence was available, “species” were groups sharing 97% or more sequence identity. By these criteria, 110 putative B.C. species matched European species and 12 B.C. species matched species exclusively found in the Americas. Of the 56 B.C. species that did not match an identified reference sequence, some may be new to science, while others likely represent described species without available sequences. By depositing sequences from B.C. specimens into GenBank and BOLD, and by providing our alignment to TreeBASE, we have supplied the resources necessary to improve accuracy in identifications of Cortinarius in future systematic and ecological studies.