Two new species of Cortinarius subgenus Telamonia section Firmiores (Agaricales, Basidiomycota) from Europe and North America

In this study, we describe two new species of Cortinarius subgen. Telamonia sect. Firmiores: Cortinarius curiosus and C. ferrugineochraceus. Both species are well supported by phylogenetic analyses and are characterized by distinct morphological features. Cortinarius curiosus is resolved within the broader /Alboviolacei clade, forming a strongly supported lineage together with the three European taxa and C. obliquus from USA. Morphologically, C. curiosus can be distinguished from the European C. acutispissipes, C. alboviolaceus, and C. paralbocyaneus by first its silvery-whitish pileus and the strongly ornamented spores. Moreover, differentiation of all these four species of the clade based on spore size and ornamentation has been established as far as possible. In Europe, C. curiosus is associated with evergreen oaks, in the USA with Quercus nigra, which can be called partially evergreen. In addition, these four species are compared with the North American Cortinarius obliquus. The second new species, Cortinarius ferrugineochraceus, is placed within the /Turgidoides clade, where it forms a distinct lineage closely related to, but clearly separable from, C. turgidoides. These two taxa are compared in detail with respect to morphology, molecular characters, and ecological preferences. Cortinarius ferrugineochraceus can easily be recognized by its white, frosty veil covering pileus and the ochraceous orange to ferrugineous colors when young. In contrast, the veil of C. turgidoides is clearly fibrillose and more distinct and the pileus is more leather-brown to ferrugineous colored. Furthermore, the taxonomic status and previously proposed synonyms of C. turgidoides are critically reassessed in light of the phylogenetic evidence presented here.