Mission impossible completed: unlocking the nomenclature of the largest and most complicated subgenus of Cortinarius, Telamonia

Abstract

So far approximately 144,000 species of fungi have been named but sequences of the majority of them do not exist in the public databases. Therefore, the quality and coverage of public barcode databases is a bottleneck that hinders the study of fungi. Cortinarius is the largest genus of Agaricales with thousands of species world-wide. The most diverse subgenus in Cortinarius is Telamonia and its species have been considered one of the most taxonomically challenging in the Agaricales. Its high diversity combined with convergent, similar appearing taxa have earned it a reputation of being an impossible group to study. In this study a total of 746 specimens, including 482 type specimens representing 184 species were sequenced. Also, a significant number of old types were successfully sequenced, 105 type specimens were over 50 years old and 18 type specimens over 100 years old. Altogether, 20 epi- or neotypes are proposed for recently commonly used older names. Our study doubles the number of reliable DNA-barcodes of species of C. subgenus Telamonia in the public sequence databases. This is also the first extensive phylogenetic study of the subgenus. A majority of the sections and species are shown in a phylogenetic context for the first time. Our study shows that nomenclatural problems, even in difficult groups like C. subgenus Telamonia, can be solved and consequently identification of species based on ITS barcodes becomes an easy task even for non-experts of the genus.

<strong><em>Cortinarius jiaoheensis</em> (Cortinariaceae), a new species of <em>Cortinarius</em> subgenus <em>Telamonia</em> section <em>Flexipedes</em>, from northeast China</strong>

“…1) show the same phylogenetic topology, with C. jiaoheensis as a new species that belongs to genus Cortinarius, subgenus Telamonia, section Flexipedes. The position of the species of Cortinarius, except for C. jiaoheensis, agrees with previous studies (Harrower et al 2011;Liimatainen et al 2020).…”

“…Based on morphological and phylogenetic characteristics, Cortinarius jiaoheensis is a well-defined species and considered new in genus Cortinarius. From interpretations based on the first extensive phylogenetic study of the subgenus (Liimatainen et al 2020) and the phylogenetic tree based on ITS (Fig. 1), we infer that C. jiaoheensis belongs to subgenus Telamonia, section Flexipedes.…”

Type studies and fourteen new North American species of Cortinarius section Anomali reveal high continental species diversity

“…Cortinarius is an important ectomycorrhizal genus in the Agaricales and is known to be the largest agaric genus worldwide (e.g., Garnica et al 2016;Liimatainen et al 2017Liimatainen et al , 2020Varga et al 2019). Species recognition based on morphology is difficult in Cortinarius lineages due to overlapping species characteristics and variation within species (e.g., Frøslev et al 2007;Niskanen et al 2009Niskanen et al , 2013Niskanen et al , 2016Liimatainen et al 2014Liimatainen et al , 2015.…”

“…However, to date, the classical European names such as C. anomalus, C. albocyaneus, C. tabularis, and others have been applied to most of the taxa in North Section editor: Zhu-Liang Yang America (Harrower et al 2011). This is a general problem based on recent phylogenetic revisions in Cortinarius (e.g., Liimatainen et al 2014Liimatainen et al , 2020Garnica et al 2016;Soop et al 2019) and similar to what has occurred in other groups of fungi (e.g., Kropp et al 2010).…”

Molecular and morphological investigation of Cortinarius bulliardii from Tokat (Turkey)

“…Cortinarius bulliardii is reported from different regions of Europe, widely distributed within the temperate-Mediterranean Europe, and from America, Asia and north Africa [15,16]. It usually found in deciduous forests (Corylus, Quercus, Tilia, Fagus) on calcareous soil [4,17].…”