The setting for the finds is one of the world’s most remarkable biogeographical transition zones. Northwestern Yunnan is where the eastern escarpment of the Qinghai–Tibet Plateau descends through successive vegetation belts into subtropical valleys carved by the Jinsha, Lancang, and Nujiang river systems. This tri-river landscape, designated a World Heritage Site by UNESCO, compresses an altitudinal gradient exceeding 5,000 meters into horizontal distances of only several tens of kilometers, generating an exceptional diversity of microhabitats.

Cortinarius is the most species-rich genus within the order Agaricales and plays a critical role in forest ecosystems as an ectomycorrhizal symbiont with a global distribution. Despite this ecological prominence, the taxonomy of the genus has historically been impeded by its immense diversity and morphological complexity. Traditionally, classification below the genus level relied heavily on macromorphology and chemotaxonomy, but a refined system proposed by Liimatainen and colleagues in 2022 integrated genomic analysis with multi-gene phylogenetics, delineating eleven subgenera including Cortinarius, Camphorati, Dermocybe, Leprocybe, Myxacium, Orellani, and Telamonia. The application of DNA barcoding, particularly using the nuclear ribosomal internal transcribed spacer (ITS) region, has revealed extensive cryptic diversity across various infrageneric groups, with many widely distributed names encompassing multiple distinct phylogenetic species that remain undescribed.

The three new species emerged from ongoing investigations of fungal diversity in China, during which researchers collected two distinct Cortinarius populations belonging to subgenus Leprocybe and section Anomali. Specimens were gathered from the Laojun Mountain Nature Reserve in Lijiang City and the Jinguangsi Nature Reserve in Yongping County, Dali, in Yunnan Province. Fresh basidiomata, the mushroom fruiting bodies, were photographed in situ before collection and transported to the laboratory in plastic collection boxes. Macroscopic features were recorded from the field photographs using standard color codes, and the specimens were dried at 40 degrees Celsius and deposited in the Herbarium of Cryptogams of the Kunming Institute of Botany, Chinese Academy of Sciences.

Microscopic examination followed established protocols. Thin sections were prepared by hand and mounted in 10 percent potassium hydroxide, stained with Congo Red when necessary, and observed with stereomicroscopes and compound microscopes equipped with digital cameras. For each mature specimen, at least 30 basidiospores and 20 basidia were measured. To resolve spore ornamentation, small hymenophoral fragments from dried specimens were mounted on aluminum stubs, coated with gold-palladium, and examined under a scanning electron microscope. DNA was extracted directly from the fruiting bodies, and the ITS region and the nuclear ribosomal large subunit (nrLSU) were amplified and sequenced.

The phylogenetic analyses combined the newly generated sequences with publicly available data from GenBank. For the subgenus Leprocybe dataset, the concatenated matrix comprised 56 sequences representing 37 taxa, aligned across 1,508 nucleotide positions, with two related species designated as outgroups. For section Anomali, the dataset comprised 120 sequences representing 63 taxa across 1,505 aligned positions. Maximum likelihood and Bayesian inference analyses yielded congruent topologies for both datasets. The results provided robust statistical support for the taxonomic independence of all three new species: Cortinarius tricholomopsoides and C. acuticonus each formed well-supported monophyletic clades within subgenus Leprocybe, and C. wudihuensis formed a well-supported monophyletic clade within section Anomali.

Cortinarius acuticonus is a striking species easily recognized in the field. Its pileus, the mushroom cap, measures 2 to 4 centimeters across and is initially acutely conical before becoming hemispherical to flattened with age. The surface is reddish brown at the disc and entirely covered with dense black scales resembling those of the genus Strobilomyces, a feature reflected in the species name, which refers to the acutely conical cap shape. The stipe bears a distinct membranous annulus, and the basidiospores are broadly ellipsoid to ellipsoid, measuring 6 to 8.5 by 4.5 to 6.5 micrometers. The species was collected in Castanopsis orthacantha forest at around 2,449 to 2,490 meters elevation in Yongping County, and is so far known only from western Yunnan.

Cortinarius acuticonus can be easily confused with the dark-scaled C. nigrosquamosus, previously recorded in Shangri-La Pudacuo National Park, but the new species differs by the complete absence of olive tinges on its pileus, finer and more densely arranged scales, the membranous annulus, and its spore dimensions. At the molecular level, sequence alignment between the two species reveals 13 significant base-pair differences, providing strong evidence for recognizing C. acuticonus as distinct. Notably, the collection sites for C. acuticonus have an average elevation of about 2,460 meters, lower than the roughly 3,500 meters recorded for C. nigrosquamosus, an altitudinal difference the authors suggest may contribute to the morphological and molecular divergences observed between the two species.

Cortinarius tricholomopsoides, by contrast, produces large basidiomata with caps 5 to 10 centimeters in diameter, initially pastel yellow and becoming light brown, covered with light-brown squamules that are dense at the disc and sparse toward the margin. Its stipe, 80 to 120 millimeters long, is cylindrical and tapers upward, covered with greyish-orange fibrillose squamules, and the mushroom has no distinctive odor. The species was found scattered or gregarious on the ground in Abies forest at 3,960 meters in the Laojunshan Nature Reserve. It is morphologically reminiscent of the European species C. cotoneus, which shares a tomentose to squamulose cap surface, but C. cotoneus displays olivaceous to brownish-olivaceous pigmentation throughout the basidiocarp, produces a pronounced raphanoid odor, and typically has a clavate to bulbous stipe and slightly larger basidiospores of 8 to 9.5 by 7 to 8 micrometers, compared with 7 to 9 by 6 to 7.5 micrometers in the new species.

Cortinarius wudihuensis, named after Wudi Lake in Shangri-La City where the type specimen was found, is a small- to medium-sized mushroom with caps of only 1 to 3 centimeters. Its pileus is brown and covered with white fibrils that tend to crack with age, the context is marbled with dull and pale violet, and the stipe carries a distinct brown ring-like zone. It was collected in Quercus aquifolioides forest at around 3,850 meters in Potatso National Park. The species is most similar to C. microalbocyaneus, described from Northeast China, sharing small basidiomata and a color transition from violaceous to brownish tones, but it can be distinguished by its slightly larger basidiospores of 7 to 9 by 5.5 to 7 micrometers, compared with 6.8 to 7.2 by 5.8 to 6.2 micrometers in C. microalbocyaneus, and its specific habitat in Shangri-La, potentially associated with Quercus aquifolioides.

The findings carry broader taxonomic significance. Species delimitation within subgenus Leprocybe has traditionally depended on characters such as dry, non-hygrophanous caps with tomentose to squamulose surfaces, subglobose to broadly ellipsoid verrucose spores, and fluorescent pigments visible under ultraviolet light. However, reliance on isolated characters is frequently inadequate, as these traits may show intraspecific variation or represent convergent evolution among distant lineages; for example, C. venetus from Europe, C. veneto-occidentalis from North America, and C. hengduanensis from China all share similar olive tones despite their geographic separation. The absence of olive tones in C. tricholomopsoides is particularly noteworthy, and the identification of C. acuticonus adds to accumulating phylogenetic evidence that olive phenotypic expression is not ubiquitous within the subgenus. Recent revisions in North America and Europe have established significant continental endemism within subgenus Leprocybe, and the new analyses corroborate this framework, showing the examined taxa represent phylogenetically divergent lineages relative to their European and American relatives. Ecologically, the new species exhibit specialized partnerships: C. tricholomopsoides is associated with Abies, while C. acuticonus occurs with Castanopsis, differing substantially from European representatives of the subgenus, which typically associate with Fagus or Quercus in temperate deciduous forests.

Section Anomali presents similar challenges. Although the section is species-rich and widely distributed, most known species were originally described from Europe and North America, and its diversity in Asia has long been severely underestimated. Molecular phylogenetics has revealed extremely high cryptic diversity and corrected historical misidentifications; the widely reported C. anomalus, for instance, has not actually been found in China, with many specimens turning out to be C. subclackamasensis or other species. Macro- and micromorphological characteristics overlap extensively across species, and unlike European species that typically have a whitish universal veil, veil color in Chinese species is highly variable. In China, 26 species of section Anomali had previously been reported, and the discovery of C. wudihuensis confirms that the diversity of this section remains incompletely understood.

The scale of recent discovery in the region is striking: in recent years, 36 new species of Cortinarius have been found in northwestern Yunnan, including two in subgenus Leprocybe and 11 in section Anomali. Only six species of subgenus Leprocybe had previously been reported from China. The authors also note a limitation of the study: incomplete coverage of nrLSU sequences for several reference species, because many earlier collections and type descriptions lack complementary nrLSU data, creating missing data zones in the multi-gene matrix. While maximum likelihood and Bayesian frameworks are resilient to such partial missing data, future systematic revisions would benefit from expanding sequencing coverage of protein-coding loci and complete ribosomal arrays across historical type materials to further stabilize deeper evolutionary branches within subgenus Leprocybe and section Anomali.

Subject of Research: Taxonomy and phylogenetics of three newly described Cortinarius mushroom species from northwestern Yunnan, China

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

Article References: Yang, Y.-W., Zhao, Q., & Zhang, Y. (2026). Morphology and multi-locus phylogeny reveal three new Cortinarius (Cortinariaceae, Agaricales) species from northwestern Yunnan, China. MycoKeys, 134, 341-361. https://doi.org/10.3897/mycokeys.134.197559

Image Credits: AI Generated

DOI: 10.3897/mycokeys.134.197559

Keywords: Cortinarius, mycology, Yunnan, new species, phylogenetics, DNA barcoding, ectomycorrhizal fungi, taxonomy, Leprocybe, Anomali, biodiversity, China