DNA Barcoding Data Reveal Important Overlooked Diversity of Cortinarius sensu lato (Agaricales, Basidiomycota) in the Romanian Carpathians

Cortinarius s.l. is a globally distributed agaricoid genus that has been well studied in Europe with over 1000 described species. However, the information about their taxonomy and diversity in eastern Central Europe is still limited. Only 124 species have been reported so far from Romania, based solely on morphological observations. The aim of this study was to re-examine the diversity of the genus Cortinarius s.l. in the Romanian Carpathian area, employing molecular phylogenetic and morphological methods. During intensive field work in the period 2017–2020, a total of 234 Cortinarius s.l. specimens were collected and studied with integrative taxonomic methods. For all the samples, we amplified and sequenced the nrDNA ITS region, which is the widely used official barcode marker of fungi. These sequences were compared to the data found in public databases (GenBank, UNITE, BOLD). Based on phylogenetic analyses, we identified 109 Cortinarius s.l. species, which represent 40 sections and 3 clades. Out of these species, 43 have previously been documented from Romania based on morphological identification methods, while 66 species are reported as new to the country.