Global mushroom look-alike splits into eight species, including new genus

A mushroom that appeared to represent a single widespread species across North America, Asia and Australia has turned out to be a taxonomic masquerade. In a global study of the Tylopilus alboater complex, an international team combined genome-scale sequencing, four-gene phylogenies and detailed microscopy to separate specimens collected from five countries into eight species distributed among five branches of the bolete family. The work reveals a striking case of how similar-looking fungi can conceal substantial evolutionary diversity, leading to the establishment of a new genus, three new names, and two newly described species.

The focal mushroom was originally described from Pennsylvania in 1822 as Boletus alboater. It was later moved among Suillus, Porphyrellus and Tylopilus as mycologists revised its classification. For decades, its identification rested heavily on the form and colour of the fruiting body, especially the dark cap, pinkish pore surface, pale flesh and the dramatic transformation from red to black after bruising. Yet fungal morphology can be highly conserved and also variable with age, weather and environment. The apparent similarity of mushrooms collected in China, Indonesia, Thailand, Australia and the United States therefore concealed lineages that the researchers found to be only distantly related within Boletaceae.

To establish the broad evolutionary position of the complex, the researchers generated three new genomes using Illumina HiSeq technology and combined them with 45 previously available genomes representing all eight subfamilies of Boletaceae. Two Suillus and two Paxillus genomes served as outgroups. An assessment of gene completeness identified 259 single-copy orthologous genes shared by all 52 genomes, and their aligned amino-acid sequences formed a matrix of 89,095 sites. Maximum-likelihood analysis strongly recovered the family’s eight-subfamily framework and showed that fungi labelled as T. alboater were polyphyletic, despite all falling within the subfamily Boletoideae.

The researchers then focused on 13 specimens: 11 identified as T. alboater from Australia, China, Indonesia, Thailand and the United States, along with two North American specimens of T. atronicotianus. A concatenated dataset of the nuclear ribosomal large subunit region, translation elongation factor 1-alpha, and the two largest RNA polymerase II subunits produced 3,056 aligned nucleotides. Maximum-likelihood and Bayesian analyses gave nearly identical topologies, placing the fungi in five generic lineages. The multi-locus tree supported many terminal relationships strongly, although some deeper branches received limited support, reflecting the smaller number of genes compared with the genome-scale analysis.

One of the most decisive results was a strongly supported lineage containing fungi from New York and China. It was unlike any previously recognized genus in the family and became Neoporphyrellus, a name that refers to its similarity in colour to Porphyrellus. The new genus contains three species: Neoporphyrellus alboater, N. atronicotianus and the newly described N. sinoalboater. Its members share dark fruiting bodies, a white-to-cream pore surface that becomes pinkish or gray, smooth spores, a trichoderm-type cap cuticle and flesh that turns reddish before eventually blackening when injured.

The revised identity of N. alboater also resolves a long-standing nomenclatural problem. Although Lewis David von Schweinitz assigned the number 864 to the specimen associated with his 1822 description, the researchers could not locate the presumed original material in several major fungal herbaria. Another specimen in Philadelphia had been collected by Persoon, who was not known to have collected in the United States, and the species has no verified European record. They therefore designated a North American specimen as a neotype, with a duplicate isoneotype, to give the name a stable modern reference point. The selected mushroom was collected at the New York Botanical Garden, about 150 kilometres from the later-cited type locality in Pennsylvania.

Beyond the new genus, the study expanded the known range of Abtylopilus, a genus previously represented by two species from China. Abtylopilus australiensis was described from a specimen collected in Queensland, Australia, and A. indonesiensis from Java, Indonesia. Both resemble the other members of their genus by producing a pale pore surface that becomes red and then black after damage. The Australian species has a reddish-brown, finely pruinose cap and stem, while the Indonesian fungus has a chocolate-brown to black cap and a pinkish-orange stem that turns deep purple or black toward the base. These records suggest that the genus is more geographically widespread than its known catalogue previously indicated.

Not every member of the old complex required a new name. Thai specimens were identified as the previously described Anthracoporus cystidiatus and Indoporus squamulosus, while a North American sample represented Tylopilus rubrobrunneus. Across the eight species, the most conspicuous field characteristic is the bruising reaction, but that feature cannot safely identify a specimen on its own. Cap colour, pore dimensions, tissue structure, cystidia and spore measurements all differ among the lineages. The new Chinese species N. sinoalboater, for example, has a gray to brownish-gray cap and a stipe that stains reddish brown before becoming black, while N. alboater has a much darker cap that becomes finely cracked with age.

The result is both a taxonomic correction and a warning for field guides, food-safety systems and biodiversity surveys. The old name T. alboater functioned as a broad label for mushrooms that looked sufficiently alike to be treated as one geographically dispersed species, but molecular evidence shows that the label united four previously recognized genera and one newly established genus. For science, the episode illustrates why fungal systematics increasingly depends on converging evidence: complete genomes establish deep relationships, targeted genes resolve nearer lineages, and microscopy supplies the structural details needed to name and diagnose species. The researchers also note that further sampling may reveal additional members of Neoporphyrellus and extend the newly documented distribution of Abtylopilus, suggesting that the true diversity of these dark, bruise-stained boletes is still only partly mapped.

Subject of Research: Phylogenomic and taxonomic revision of the global Tylopilus alboater mushroom complex

Article Title: Global diversity of the Tylopilus alboater complex ( Boletaceae , Boletales ): new genus and species, and typification of the name Boletus alboater

Article References: Li, J., Halling, R. E., Osmundson, T. W., Yang, Z. L., & Li, Y.-C. (2025). Global diversity of the Tylopilus alboater complex (Boletaceae, Boletales): new genus and species, and typification of the name Boletus alboater. IMA Fungus, 16, Article e159676. https://doi.org/10.3897/imafungus.16.159676

Image Credits: AI Generated

DOI: 10.3897/imafungus.16.159676

Keywords: fungal taxonomy, mushroom diversity, phylogenomics, Boletaceae, Neoporphyrellus, Abtylopilus, species delimitation, molecular evolution, mycology, Global, diversity, Tylopilus