Four New Wood-Decay Fungi Uncovered in East China’s Forests

Deep in the subtropical forests of eastern China, researchers have identified four previously unknown species of wood-inhabiting fungi, expanding our understanding of fungal diversity in the region. The new species, described in the journal MycoKeys, belong to the genus Botryobasidium, a group of white-rot fungi that play a crucial role in breaking down cellulose and lignin in dead wood. The discovery was made through a combination of detailed morphological examination and molecular phylogenetic analysis, offering fresh insight into how these organisms contribute to nutrient cycling and carbon turnover in forest ecosystems.

Wood-inhabiting fungi are among the most important decomposers in forest environments. By degrading cellulose and lignin, they facilitate the decomposition of fallen branches and rotting trunks, driving the flow of energy and nutrients through the ecosystem. Botryobasidium species are predominantly white-rot fungi, meaning they cause a distinctive type of decay that bleaches the wood they colonise. They commonly grow on rotten wood and fallen branches of both angiosperms and gymnosperms, including bamboo, oak, fir, pine and spruce. Some species have even been reported from soil or from the mature fruiting bodies of other fungi.

The genus Botryobasidium was first proposed in 1931 by Dutch mycologist Donk, who observed that its members bear barrel-shaped basidia with four sterigmata and densely ornamented basidiospores. Over the decades, the genus has undergone extensive morphological revision, with 49 species accepted worldwide by the year 2000. Molecular phylogenetic studies have consistently shown that Botryobasidium forms a well-supported monophyletic group, meaning all its species share a common ancestor. According to Index Fungorum and MycoBank, 120 names have been recorded for the genus globally, though many are invalidly published or have been transferred to other genera. Of these, 34 species have been confirmed by molecular sequence data, and 22 species have been reported in China.

During field surveys of wood-inhabiting fungi in eastern China, researchers collected six specimens that morphologically corresponded to Botryobasidium. Phylogenetic analysis based on the internal transcribed spacer (ITS) region and the nuclear large subunit (nLSU) ribosomal RNA gene was conducted to determine their placement within the genus. The six specimens formed four distinct lineages within the Botryobasidium clade, each distinguishable from their phylogenetically related and morphologically similar species. Based on the combined morphological and molecular evidence, the team described them as four new species: Botryobasidium fujianensis, B. fusisporellum, B. subconiferarum and B. macrosporum.

The phylogenetic analysis used a combined dataset of ITS and nLSU sequences from 65 fungal specimens representing 39 taxa. The final alignment contained 2,101 nucleotide positions. Maximum Likelihood and Bayesian Inference methods were employed to construct the phylogenetic tree, with branch support assessed through bootstrap analysis with 1,000 replicates and Bayesian posterior probabilities. The results showed that the newly collected specimens formed four well-supported distinct lineages. Botryobasidium fujianensis grouped with B. aureum, B. indicum, B. coniferarum and B. subconiferarum with strong support, while B. fusisporellum formed an independent lineage not closely related to any other known species. Botryobasidium macrosporum was closely related to B. laeve, B. vagum, B. incanum and B. subincanum with high support.

Each of the four new species displays a unique combination of morphological features. Botryobasidium fujianensis is characterised by a hypochnoid, floccose to cottony, white to greyish-white hymenial surface, a monomitic hyphal system with simple septa, the presence of tubular cystidioid structures, barrel-shaped basidia with four or six sterigmata, and pip-shaped basidiospores measuring 6.0 to 7.9 by 2.3 to 3.4 micrometres. The species was collected on rotten wood of Chinese fir in Wuyishan National Nature Reserve in Fujian Province and on a fallen branch of pine in Tianbaoyan National Nature Reserve.

Botryobasidium fusisporellum shares a similar hymenial surface with B. fujianensis but is distinguished by its long barrel-shaped basidia bearing two or four sterigmata and its fusiform basidiospores measuring 5.3 to 6.5 by 2.3 to 3.0 micrometres. This species was found on rotten wood and on soil over stone in Wanmulin Nature Reserve, also in Fujian Province. In the phylogenetic tree, B. fusisporellum formed an independent lineage with maximum support, indicating it is not closely related to other sequenced species in the genus. Morphologically, it resembles B. chilense and B. daweishanense in having fusiform basidiospores, but the latter two species have wider basidia and larger basidiospores.

Botryobasidium subconiferarum is notable for being the only one of the four new species observed to produce conidiophores, the asexual reproductive structures. It is characterised by slightly barrel-shaped basidia with four sterigmata, subcylindrical conidiophores, and pip-shaped basidiospores measuring 6.2 to 8.6 by 2.3 to 3.7 micrometres. The holotype was collected on a fallen angiosperm branch in Tianhuajing National Forest Park in Jiangxi Province. The species name refers to its similarity to B. coniferarum, though it differs from that species by having a floccose rather than arachnoid hymenial surface and by the presence of cystidioid structures, which B. coniferarum lacks.

Botryobasidium macrosporum stands out for having the largest basidiospores among the four new species, measuring 9.4 to 11.0 by 4.8 to 5.9 micrometres. These fusiform spores carry one to three guttules, small oil droplets visible under the microscope. The species produces slightly barrel-shaped basidia with four to six sterigmata and was collected on an angiosperm trunk in Anhui Province. In the phylogeny, B. macrosporum is closely related to B. incanum, B. subincanum, B. laeve and B. vagum, but can be easily distinguished from all of them by its cystidioid structures and larger basidiospores. The species epithet directly reflects its most striking feature: large spores.

Pairwise ITS sequence divergence between the new species and their closest relatives further confirmed their status as distinct taxa. Botryobasidium fujianensis differed by 5.55 percent from B. aureum, 6.56 percent from B. coniferarum and 7.03 percent from B. indicum. Botryobasidium subconiferarum differed by 4.46 percent from B. aureum and 6.70 percent from B. coniferarum. Botryobasidium macrosporum showed 3.50 percent divergence from B. incanum and 3.15 percent from B. laeve. These levels of sequence divergence, combined with consistent morphological differences, provide robust evidence that the four lineages represent species new to science.

The discovery of these four new species in eastern China expands the known global diversity of Botryobasidium and provides additional morphological and molecular data for the genus. The researchers also compiled a morphological comparison of 20 Botryobasidium species with molecular data from China, creating a reference for future taxonomic studies. Beyond taxonomy, the findings carry broader ecological and evolutionary significance. Some Botryobasidium species possess diverse enzymes capable of acting on crystalline cellulose, and the genus may manifest a decay mode that is plesiomorphic, or ancestral, for the entire class Agaricomycetes. Understanding the diversity of this lineage is therefore important not only for cataloguing fungal species but also for reconstructing the origin of wood-decay mechanisms in one of the largest groups of mushrooms and their relatives.

Wood-inhabiting fungi in China remain insufficiently documented despite their crucial roles in forest ecosystem functioning. This study adds four new species to the national inventory and underscores the value of combining classical morphological observation with modern molecular phylogenetics. As field surveys continue across China’s diverse subtropical and temperate forests, further discoveries of novel fungal species are likely, each contributing to a more complete picture of the decomposer communities that sustain forest health and drive the global carbon cycle.

Subject of Research: Morphological characteristics and phylogenetic analyses revealed four new wood-inhabiting species of Botryobasidium (Cantharellales, Basidiomycota) from East China

Article Title: Morphological characteristics and phylogenetic analyses revealed four new wood-inhabiting species of Botryobasidium ( Cantharellales , Basidiomycota ) from East China

Article References: Jing, W., Li, W.-Y., Papp, V., Guan, Q.-X., Zheng, Z.-W., Cui, Y.-J., & Wu, F. (2026). Morphological characteristics and phylogenetic analyses revealed four new wood-inhabiting species of Botryobasidium (Cantharellales, Basidiomycota) from East China. MycoKeys, 139, 321-339. https://doi.org/10.3897/mycokeys.139.206012

Image Credits: AI Generated

DOI: 10.3897/mycokeys.139.206012

Keywords: mycology, fungi, biodiversity, taxonomy, phylogenetics, forest ecology, new species, China, Morphological, characteristics, phylogenetic, analyses