The new study stems from field surveys conducted between 2024 and 2025 in Yunnan Province and the Xizang Autonomous Region, during which researchers collected Phaeocollybia specimens and photographed fresh basidiomata in situ, recording collection site, date, habitat, substrate, elevation, and geographical coordinates. All specimens were dried at 55 degrees Celsius and deposited in the Herbarium of Cryptogams at the Kunming Institute of Botany, Chinese Academy of Sciences, and the Herbarium of Dali University. Combining detailed morphological observation with multilocus phylogenetic analyses of internal transcribed spacer (ITS), nuclear ribosomal large subunit (nrLSU), and second-largest subunit of RNA polymerase II (rpb2) sequence data, the team recognized two new species, Phaeocollybia dingjieensis and Phaeocollybia lulangensis, and one species newly recorded for China, Phaeocollybia attenuata, previously known only from North America.

Phaeocollybia dingjieensis, whose Chinese name is Ding Jie An Jin Qian Jun, was collected in Dingjie County in the Xizang Autonomous Region at an elevation of 3,332 meters, with the holotype gathered on 25 July 2025. The species is distinguished by a light orange pileus with dark orange vertical stripes, a long hollow stipe that turns dark desaturated red at maturity, limoniform basidiospores measuring 7.6 to 9.2 by 4.6 to 5.8 micrometers with verruculose ornamentation that leaves the apex and apiculus smooth, and the absence of pleurocystidia. Clamp connections occur occasionally. The cap measures 1.5 to 2.5 centimeters across and is paraboloid to broadly conical with an acute papilla at the center, while the stipe runs 8 to 10 centimeters long. The fungus was found solitary or scattered in broad-leaved forests, and tibiiform diverticula were abundant on the pseudorrhizal pellis.

Phaeocollybia lulangensis, named for Lulang Town in Linzhi City where the holotype was collected at 3,419 meters on 18 July 2025, is set apart by a pure orange to strong orange pileus with an oily to subwaxy luster, a hollow stipe with a root-like pseudorhiza, limoniform basidiospores of 5.3 to 6.3 by 3.8 to 4.6 micrometers bearing a distinct suprahilar depression, and the absence of pleurocystidia. Its cap spans 2.5 to 4.0 centimeters and is broadly conical to conical with a subumbonate center, deepening to strong orange at the center and toward the margin. The spore surface is smooth to rarely verruculose, and the cheilocystidia are narrowly cylindrical to lageniform with long rostrate apices. Clamp connections were absent in all tissues examined. A paratype was collected in Mi Lin City at 3,074 meters on the same date.

The third finding concerns Phaeocollybia attenuata, a species originally described by Smith in 1937 and previously known only from North America. Two Chinese collections were made in Jianchuan County, Dali City, Yunnan Province, at an elevation of 2,441 meters, in September 2024. The Chinese material closely matches the holotype description in essential diagnostic features, including a long tapering pseudorhiza, a hollow cartilaginous stipe, the absence of clamp connections except for very rare and scattered ones in the stipitipellis, and undifferentiated cystidia. The Chinese specimens do show some variation: the pileus is moderate orange with conspicuous pale orange radial streaks, a feature not mentioned in the original description, and the basidiospores are slightly larger, averaging 8.80 by 5.87 micrometers and limoniform with a distinct apical papilla, whereas Smith described smaller, almond-shaped spores of 7 to 8 by 4 to 4.5 micrometers. Microscopic examination also revealed abundant tibiiform diverticula on the pseudorhizal pellis, a characteristic structure of the genus not noted in the protologue.

The phylogenetic work behind these conclusions was substantial. The researchers generated 21 new sequences from seven samples, seven each of ITS, nrLSU, and rpb2, all deposited in the NCBI database. In total, 150 sequences were used, drawn from 91 samples representing 42 species, with Galerina semilanceata designated as the outgroup. The concatenated three-locus alignment totaled 2,030 base pairs including gaps. Maximum likelihood analysis was run in RAxML-HPC2 with the GTR+G+I substitution model and 1,000 rapid bootstrap replicates, while Bayesian inference was performed in MrBayes with partitions by gene region and models selected under the Akaike information criterion. The two approaches produced nearly identical topologies. A clade was considered strongly supported if it received bootstrap support of at least 75 percent and a Bayesian posterior probability of at least 0.90.

The resulting tree placed the seven Chinese samples in three well-supported independent clades. Phaeocollybia dingjieensis formed a strongly supported trichotomy with P. elegans, a New Zealand species, with 100 percent maximum likelihood support and a posterior probability of 1.00. Phaeocollybia lulangensis, supported at 100 percent in the likelihood analysis, formed a sister clade to the clade comprising P. ochrilata and P. jennyae. The newly recorded P. attenuata collections from China formed a sister clade with a P. attenuata specimen from the USA, albeit with poor bootstrap support. Sequence comparisons quantified the divergences: the ITS difference between the P. dingjieensis holotype and P. elegans was 10.03 percent, that between the P. lulangensis holotype and P. ratticauda was 6.14 percent, and the Chinese P. attenuata collection differed from two North American P. attenuata specimens by 2.69 percent and 4.26 percent respectively. Given its position in the tree, the morphological match with the protologue, and the current absence of ex-type sequences for P. attenuata, the authors tentatively regard the Chinese collection as a new record for the country.

Morphological comparisons reinforce each delimitation. Phaeocollybia dingjieensis resembles P. amygdalospora in its orange to yellowish-brown cap tones and brownish stipe, but the latter has a smaller pileus that flattens with age and shows purplish tones, a shorter stipe, typically claviform basidia, and a complete lack of clamp connections in all tissues. Against P. elegans, the new species differs in cap size, coloration with dark moderate orange vertical stripes, the acute central papilla, a longer stipe, substantially larger spores averaging 8.4 by 5.2 micrometers, and longer cheilocystidia. Phaeocollybia lulangensis is morphologically similar to P. chefensis from the Oregon coast, but that species has a distinctive uniform copper metallic sheen when dry, larger basidiospores averaging 8.9 by 5.6 micrometers that are consistently verruculose to verrucose, and tibiiform cheilocystidia with thick-walled refractive necks and capitula. It also contrasts with P. ratticauda of New Zealand, which has a dry reddish-brown to yellowish-brown pileus, pale violet lamellae, and heavily verrucose spores.

The study places these findings in a broader biogeographic context. Globally, Phaeocollybia species are predominantly distributed in temperate regions of the Northern Hemisphere, with major diversity hotspots in the Pacific Northwest of North America and in subtropical to tropical montane regions of Asia and the Neotropics, notably southwestern China, Mexico, and Colombia. Despite their transoceanic separation, these regions share perhumid forest ecosystems with persistently high atmospheric humidity and substantial annual precipitation, from temperate rainforests to tropical montane cloud forests and the monsoon-influenced subtropical broad-leaved and mixed forests of southwestern China. This aligns with the genus’s known ecological preference for mesic environments. To date, 19 species of Phaeocollybia have been documented in China, including the three reported in this study, and all Chinese records are confined to regions south of the Yangtze River across six provincial-level areas: Yunnan, Sichuan, Xizang, Fujian, Guangdong, and Hainan.

The authors argue that Phaeocollybia diversity in China remains substantially underestimated. Only 15 species had been reported from the country before this study’s updated count, whereas Norvell and Exeter documented 25 species from the temperate coastal regions of the Pacific Northwest alone. The absence of records from northern or northeastern China may reflect historical undersampling rather than climatic constraints, since suitable mesic forest habitats occur at higher latitudes in the country. Southwestern China stands out as the clear national center of diversity, harboring the two newly described species along with several previously reported taxa, a concentration that echoes patterns seen in other ectomycorrhizal agaric genera. The paper also provides an updated dichotomous key to the 15 species of Phaeocollybia currently known from China and notes that, because sequence data from type specimens are still lacking for many species, future studies should prioritize epitypification supported by molecular data to stabilize nomenclature and resolve prevailing taxonomic uncertainties.

Subject of Research: Taxonomy and phylogeny of Phaeocollybia mushrooms in southwestern China

Article Title: Morphology and phylogenetic analyses reveal two new species and a new record of Phaeocollybia ( Agaricales , Hymenogastraceae ) from southwestern China

Article References: Li, R.-Y., Zhao, D.-F., Li, Y.-T., Luo, Y., Li, E.-X., Song, H.-B., Shen, H.-W., Luo, Z.-L., & Tang, S.-M. (2026). Morphology and phylogenetic analyses reveal two new species and a new record of Phaeocollybia (Agaricales, Hymenogastraceae) from southwestern China. MycoKeys, 142, 215–238. https://doi.org/10.3897/mycokeys.142.206931

Image Credits: AI Generated

DOI: 10.3897/mycokeys.142.206931

Keywords: Phaeocollybia, Hymenogastraceae, Agaricales, new species, China, Yunnan, Xizang, phylogenetics, ITS, taxonomy, fungal diversity, mycology