Morphology and multi-locus phylogeny reveal three new Cortinarius (Cortinariaceae, Agaricales) species from northwestern Yunnan, China

Yunnan’s complex topography and pronounced geographic heterogeneity, together with marked climatic variability, luxuriant vegetation, and the seasonal influx of warm, moisture-laden air masses from the Indian and Pacific Oceans, have created abundant refugial habitats throughout the Quaternary glaciations. These combined abiotic and biotic factors have made the region highly favorable for the survival, diversification, growth, and reproduction of higher fungi. This study reports three new species: Cortinarius acuticonus , C. tricholomopsoides , and C. wudihuensis from the subalpine and alpine forests of northwestern Yunnan, China, identified through morphological investigations and multi-locus phylogenetic analyses. Cortinarius acuticonus and C. tricholomopsoides are placed in the subgenus Leprocybe . Cortinarius acuticonus is distinguished by an acutely conical pileus with dense black, Strobilomyces -like scales and a distinct membranous annulus. In contrast, Cortinarius tricholomopsoides exhibits large, pale yellow basidiomata and forms associations with Abies species. Cortinarius wudihuensis , assigned to section Anomali , is characterized by small basidiomata with violaceous to brownish tones, an association with Quercus aquifolioides , and larger, broadly ellipsoid basidiospores (7–9 × 5.5–7 μm). These findings underscore the substantially underestimated diversity of Cortinarius in the high-altitude regions of Yunnan and offer important insights into the ecological specialization and evolutionary divergence of Asian Cortinarius lineages.