Researchers have formally described three previously unknown species of Russula in the subsection Cyanoxanthinae, a lineage of ectomycorrhizal mushrooms distinguished by a combination of microscopic structures, subtle chemical reactions and DNA sequence differences. The taxonomic study, based on fungi collected in Hubei and Fujian provinces between 2022 and 2024, names Russula purpureogrisea, Russula subpallescens and Russula wuyishanensis. Their descriptions integrate field observations, detailed microscopy and phylogenetic analyses of four gene regions, showing why apparently similar mushrooms can nevertheless represent distinct evolutionary lineages.
The new species were found during macrofungal diversity surveys in mixed coniferous and broad-leaved forests containing Cupressaceae, Pinaceae, Theaceae and Fagaceae. Such forests are major habitat for Russula, whose species typically form ectomycorrhizal associations with trees. These partnerships involve fungal networks in plant roots and are described in the study as important for plant stress tolerance, root proliferation and nutrient acquisition. The discoveries therefore expand the documented diversity of ecologically important forest fungi, although the research did not directly test the functions of the three new species in living trees.
Russula is one of the most species-rich fungal genera worldwide, with an estimated minimum of 2,000 accepted species, and its members occur in ecosystems ranging from Arctic tundra to tropical forests. Many species resemble one another under the naked eye, and the genus is also known for substantial variation in features such as cap colour. The authors note that earlier morphology-based identifications can consequently obscure cryptic lineages and lead to misidentification. Molecular systematics has become essential for resolving these cases, particularly within Cyanoxanthinae, a group within the subgenus Heterophyllidiae.
The subsection was assigned to the three new taxa through a combination of anatomical and chemical characters: an inamyloid suprahilar region on the basidiospores, a metachromatic reaction of the pileipellis in cresyl blue, and unicellular pileocystidia. For each specimen, the researchers measured at least 40 basidiospores, 20 basidia and 20 cystidia. They also recorded the dimensions and ornamentation of spores, examined cystidia and pileipellis tissues, and used scanning electron microscopy to illustrate spore surfaces. Fresh collections were photographed and described in the field, while dried specimens were deposited in the Fungal Herbarium of Jiangxi Agricultural University.
Genetic evidence came from four loci: the internal transcribed spacer region, nuclear large subunit, mitochondrial small subunit and RNA polymerase beta subunit second largest subunit, or rpb2. The analysis contained 2,713 aligned characters from 57 taxa, including 372 parsimony-informative sites. Maximum likelihood and Bayesian inference analyses placed all three new species within Clade 1 of Cyanoxanthinae, and each formed an independent branch. Russula wuyishanensis and Russula purpureogrisea received complete support for their individual lineages, with ultrafast bootstrap values of 100% and Bayesian posterior probabilities of 1. Russula subpallescens grouped with Russula perviridis, but that broader relationship had unstable statistical support.
Russula purpureogrisea, whose name refers to its purplish-grey cap, is characterised by small to medium-sized fruiting bodies with a dark greyish-ruby to greyish-brown pileus. Its cap measures 20–50 mm across, and its crowded, unforked gills number 14–15 per centimetre near the margin. The spores measure 6.1–8.4 by 5.2–6.8 micrometres and bear mostly isolated, obtuse-conical warts, occasionally joined by fine lines or low ridges that sometimes form a local subreticulum. The authors distinguished it from related taxa through its pileus colour, spore ornamentation, cystidial dimensions and other structural details.
Russula subpallescens has a pinkish-white cap about 55 mm in diameter, crowded and equal-length gills with intervenose veins, and a hollow white stipe that develops pale yellow to maize-yellow patches with age or prolonged bruising. Its spores measure 6.7–8.4 by 5.8–6.8 micrometres, with dispersed amyloid warts, 0.3–0.8 micrometres high, frequently connected by short lines to produce a nearly subreticulate pattern. The species occupied a mixed coniferous and broad-leaved forest at an elevation of 1,526 metres in Xingshan County, Hubei. Its closest phylogenetic associate, R. perviridis, differs in having a greenish cap, reticulate spore ornamentation and frequently forked gills.
Russula wuyishanensis was named for Wuyishan, where the type specimen was collected in Fujian. It has a 45–75 mm reddish-grey to purplish-brown cap, sometimes with a greyish to dark greyish-green centre, and decurrent gills containing three types of shorter lamellulae. The context turns yellowish-brown when bruised. Its spores measure 6.2–9.7 by 5.2–7.7 micrometres and carry many obtuse warts that are sometimes connected by short lines or ridges and occasionally form a subreticulum. Three Fujian collections supported the description, with the holotype collected at 478 metres above sea level in 2023.
The findings also expose a limitation in a proposed visual division of Cyanoxanthinae. Earlier work divided the subsection into two major clades partly according to whether connections between spore warts were common or predominantly absent. Russula subpallescens fits that pattern because its warts are frequently joined by short lines. Russula purpureogrisea and R. wuyishanensis nevertheless clustered in the same molecular clade even though their spore ornamentation consists mainly of isolated warts with only partial or occasional connections. The authors therefore conclude that the boundary between the two clades is more complex than a simple count of spore-wart connections can indicate. Broader geographic sampling is needed to clarify the evolutionary history, ecology and full species diversity of the subsection in subtropical China.
Subject of Research: Taxonomic discovery of three Russula subsection Cyanoxanthinae species in subtropical China
Article Title: Three new species of Russula subsect. Cyanoxanthinae from subtropical China ( Russulales , Russulaceae )
Article References: Zhong, B.-J., Zeng, H., Wang, S.-N., & Yan, J.-Q. (2026). Three new species of Russula subsect. Cyanoxanthinae from subtropical China (Russulales, Russulaceae). MycoKeys, 134, 291-312. https://doi.org/10.3897/mycokeys.134.195117
Image Credits: AI Generated
DOI: 10.3897/mycokeys.134.195117
Keywords: Russula, Cyanoxanthinae, fungal taxonomy, mushroom diversity, ectomycorrhizal fungi, subtropical forests, phylogenetics, Hubei, Fujian, cryptic species, Three, species
