# Xerocomus
**Xerocomus** is a genus of ectomycorrhizal bolete fungi in the family [Boletaceae](https://www.edgepedia.org/boletaceae) (order Boletales), established by the French mycologist Quélet in 1887 and typified by *[Xerocomus subtomentosus](https://www.edgepedia.org/xerocomus-subtomentosus)* (L.) Quél., the velvet bolete[1](https://fungalpedia.org/glossary/xerocomus/). Species in the broad sense have dry, finely felted caps and pores whose anatomy, particularly the hymenophoral trama, defines the genus microscopically[1](https://fungalpedia.org/glossary/xerocomus/) • [2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c).
| Key fact | Detail |
|---|---|
| Classification | Boletaceae, Boletales, Agaricomycetes, Basidiomycota, Fungi[1](https://fungalpedia.org/glossary/xerocomus/) |
| Established | Quélet, 1887, in *La Flore des Vosges, Champignons*, page 109; type species *X. subtomentosus* (L.) Quél.[1](https://fungalpedia.org/glossary/xerocomus/) • [2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c) |
| Synonym | Versipellis Quél.[3](https://species.data.kew.org/species/18763) |
| Species count | Around 115 species currently accepted under Species Fungorum (2023)[1](https://fungalpedia.org/glossary/xerocomus/) |
| Defining character of X. s.str. | Bacillate (rod-like) basidiospore ornamentation[1](https://fungalpedia.org/glossary/xerocomus/) |
| Phylogenetic status | Non-monophyletic as broadly circumscribed; multi-gene analyses resolve six lineages, including Xerocomus s.str., Hemileccinum, and Xerocomellus[1](https://fungalpedia.org/glossary/xerocomus/) |
| Ecology | Ectomycorrhizal, associated with trees such as Nothofagus, Leptospermum, Pinus, and Pseudotsuga[2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c) |
## History and taxonomic instability
Quélet introduced *Xerocomus* in 1887 within *La Flore des Vosges*, and the genus was typified by *X. subtomentosus* in 1888[1](https://fungalpedia.org/glossary/xerocomus/). Because classification of Basidiomycetes traditionally relied on the morphology of the fruiting bodies (basidiomata), the name was applied broadly to a diversity of dry-capped boletes, which reflected the heterogeneity of the group and generated many synonyms[1](https://fungalpedia.org/glossary/xerocomus/). Some mycologists merged Xerocomus into *Boletus* L., while others treated it as distinct[1](https://fungalpedia.org/glossary/xerocomus/). A proposal based on the hymenophoral trama (the tissue of the pore layer) allowed European species of *Boletus* to be distinguished from *Xerocomus*, but non-European species remained ambiguous[1](https://fungalpedia.org/glossary/xerocomus/).
**Molecular phylogenetics changed the picture.** Studies have inferred that Xerocomus in the broad sense is non-monophyletic[1](https://fungalpedia.org/glossary/xerocomus/). Klofac and Krisai-Greilhuber (1992) had placed many boletes with dry, velvety caps in Xerocomus, but even this circumscribed genus proved polyphyletic[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7453129/). Šutara (2008) established the genus Xerocomellus to accommodate *X. chrysenteron* and its relatives, the "cracked-cap boletes" that develop areolate (cracked into small plates) cap surfaces[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC7453129/). Multi-gene analyses using LSU, tef1-α, rpb1, and rpb2 revealed six lineages within the former Xerocomus: Xerocomus sensu stricto, *Hemileccinum* Šutara, *Xerocomellus* Šutara, and three other unnamed clades[1](https://fungalpedia.org/glossary/xerocomus/). Later work also segregated *Hortiboletus* (the former *Xerocomus rubellus* complex) as a sister genus to Xerocomellus[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC12179652/).
## Morphology of Xerocomus sensu stricto
Several characters are typical of Xerocomus species in the strict sense: the ornamentation of the basidiospores, a phylloporoid hymenophoral trama of non-gelatinous tissue, a non-glutinous trichoderm-type pileipellis (cap surface of loosely arranged hyphal chains), and a non-gelatinous, loosely arranged, divergent lateral stratum in the peripheral layers of the stipe[1](https://fungalpedia.org/glossary/xerocomus/). Spore ornamentation has become an important character for delimiting taxa in the genus[1](https://fungalpedia.org/glossary/xerocomus/).
Members of Xerocomus s.str. show a slender, less fleshy habit than typical *Boletus*, a pileus surface that is never viscid or glutinous when wet, and angular pores about 1–3 mm across at maturity on adnate tubes roughly 15 mm long[1](https://fungalpedia.org/glossary/xerocomus/). In New Zealand material, the caps are described as dry and finely felted, and the genus is defined by the anatomical structure of the pores[2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c).
## Species diversity and distribution
Species Fungorum currently documents around 115 species in the genus[1](https://fungalpedia.org/glossary/xerocomus/). In Europe, where the taxonomy has been described as remarkably confused for so small a group, the number of species involved was estimated at 16 to 22[6](https://www.sciencedirect.com/science/article/pii/S0953756205000584).
**Regional diversity is still being worked out.** In China, taxonomic and phylogenetic studies of the subfamily Xerocomoideae confirmed eight previously described Xerocomus species and described two new ones, within a subfamily of 10 genera and 97 accepted Chinese species[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC10825750/). In New Zealand, at least seven indigenous species occur, most under southern beech (*Nothofagus*), with *X. griseoolivaceus* under tea-tree (*Leptospermum*); introduced species there include *X. chrysenteron* under exotic broadleafed trees and *X. rubellus* under *Salix*[2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c). In Malesia, work on defining Xerocomus s.str. has continued, with basidiospore morphology among the characters used to separate the genus from related taxa[8](https://www.researchgate.net/publication/375073233_Defining_Xerocomus_sstr_Boletaceae_in_Malesia).
## Ecology and human use
Xerocomus species are ectomycorrhizal, forming symbiotic root associations with trees; New Zealand records list hosts including *Juniperus*, *Leptospermum*, *Nothofagus menziesii*, *Nothofagus solandri*, *Populus*, and *Pseudotsuga menziesii*[2](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c). The type species, *X. subtomentosus*, is recognized by yellowish pores that turn blue when damaged and flesh that does not change color when cut; it fruits from July to November in European coniferous and mixed forests, mainly under pines and firs, and is gathered for food[9](https://www.huffingtonpost.es/sociedad/los-espanoles-suelen-topar-bosques-hongo-mas-sabroso-boletus.html).
## References
1. [Bera I. et al. (2024). Xerocomus. Fungalpedia – Note 204.](https://fungalpedia.org/glossary/xerocomus/)
2. [Xerocomus Quél. 1887, Biota of NZ, Manaaki Whenua – Landcare Research.](https://biotanz.landcareresearch.co.nz/scientific-names/1cb1abc6-36b9-11d5-9548-00d0592d548c)
3. [Xerocomus Quél., Kew species data (Index Fungorum accepted name and synonyms).](https://species.data.kew.org/species/18763)
4. [Frank J.L., Siegel N., Schwarz C.F., Araki B., Vellinga E.C. (2020). Xerocomellus (Boletaceae) in western North America. Fungal Systematics and Evolution 6: 265–288.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7453129/)
5. [Biketova A.Yu. et al. (2025). Morphological and molecular re-assessment of European and Levantine species of the genus Hortiboletus (Boletaceae). IMA Fungus 16.](https://pmc.ncbi.nlm.nih.gov/articles/PMC12179652/)
6. [Detection of species within the Xerocomus subtomentosus complex in Europe using rDNA–ITS sequences. Mycological Research.](https://www.sciencedirect.com/science/article/pii/S0953756205000584)
7. [The subfamily Xerocomoideae (Boletaceae, Boletales) in China.](https://pmc.ncbi.nlm.nih.gov/articles/PMC10825750/)
8. [Lee S.M.L., Helfer S., Watling R. (2023). Defining Xerocomus s.str. (Boletaceae) in Malesia. Journal of Tropical Biology & Conservation 20: 27–43.](https://www.researchgate.net/publication/375073233_Defining_Xerocomus_sstr_Boletaceae_in_Malesia)
9. [El boleto aterciopelado (Xerocomus subtomentosus), HuffPost España.](https://www.huffingtonpost.es/sociedad/los-espanoles-suelen-topar-bosques-hongo-mas-sabroso-boletus.html)
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*Topic: Encyclopedia › Life and health › Microorganisms and fungi › Fungi and mycology › Basidiomycete taxa › Agaricomycetes › Boletales › Other Boletaceae genera › Xerocomus and xerocomoid segregates*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Oct 11, 2026; Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license