''Xerocomellus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

in the family

Boletaceae The Boletaceae are a family of mushroom-forming fungi, primarily characterised by small pores on the spore-bearing hymenial surface (at the underside of the mushroom), instead of gills as are found in most agarics. Nearly as widely distributed ...

. The genus, as it was described in 2008, contained 12 species. However '' X. rubellus'' and '' X. engelii'' were transferred to the new genus '' Hortiboletus'' and '' X. armeniacus'' was transferred to the new genus '' Rheubarbariboletus'' in 2015. Molecular analysis supports the distinction of ''Xerocomellus'' species from ''

Boletus ''Boletus'' is a genus of mushroom-producing fungi, comprising over 100 species. The genus ''Boletus'' was originally broadly defined and described by Carl Linnaeus in 1753, essentially containing all fungi with hymenial pores instead of ...

'' and '' Xerocomus'', within which these species were formerly contained. ''Xerocomellus'' in fact is only distantly related to '' Xerocomus'' and is most closely related to ''

Tylopilus ''Tylopilus'' is a genus of over 100 species of mycorrhizal bolete fungi separated from ''Boletus''. Its best known member is the bitter bolete (''Tylopilus felleus''), the only species found in Europe. More species are found in North America, s ...

'', ''

'' sensu stricto, '' Porphyrellus'', '' Strobilomyces'', and '' Xanthoconium''.

Taxonomy

Members of the genus had been classified either in the genus ''Boletus'' or ''Xerocomus'' until Czech mycologist Josef Šutara examined a number of species and concluded that there was a defined group containing ''X. chrysenteron'', ''X. armeniacus'' and relatives that are distinct morphologically from the group containing ''

Xerocomus subtomentosus ''Xerocomus subtomentosus'', commonly known as suede bolete, brown and yellow bolete , boring brown bolete or yellow-cracked bolete, is a species of bolete fungus in the family Boletaceae. The fungus was initially described by Carl Linnaeus in 17 ...

'' and related species. He deferred fully delimiting the genus until genetic work confirmed their distinctness. Previously, Manfred Binder had coined the term ''Paraxerocomus'' for the group but this was not officially published. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is the red-cracked bolete ('' Xerocomellus chrysenteron'').

Genetic analysis Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of ...

published in 2013 showed that ''X. chrysenteron'' and ''X. zelleri'' form a ''Xerocomellus'' clade within a larger group informally called "anaxoboletus" in the

Boletineae The Boletineae are a suborder of the fungal order Boletales. Families in the Boletineae include the Boletaceae and the Paxillaceae. Taxa *Paxillaceae **'' Alpova'' **'' Austrogaster'' **'' Gyrodon'' **'' Hydnomerulius'' **'' Meiorganum'' **'' ...

. It appears to have affinities with what was then known informally as the "rubellus clade", which contained the species ''X. rubellus'' and ''X. armeniacus'', now known as '' Hortiboletus rubellus'' and '' Rheubarbariboletus armeniacus'' respectively. The same study found ''Xerocomellus'' to be more distantly to a 'badius' clade containing ''Boletus badius'', now known as '' Imleria badia'', and relatives. Other clades in the group include the porcini (true ''

'' species) and '' Strobilomyces'' clades, species currently designated '' Xerocomus'' (the species are not true ''Xerocomus'' species), and smaller genera whose relationships are unclear.

Description

Members of the genus have small to medium-size

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

with more slender stipes compared with other boletes. They are often brightly coloured. The caps are dry and do not become sticky when wet. Their cuticle tissue is a palisadoderm, comprising parallel or roughly parallel hypha arranged in an anticlinal fashion. The palisoderm, which is generally between 120 and 350 μm thick (although extremes of 80 μm and 500 μm are known), maintains its characteristic arrangement for longer periods than other boletes. The tubes are generally yellow and

adnate Adnate may refer to: * Adnation, in botany, the fusion of two or more whorls of a flower * Adnate, in mycology, a classification of lamellae (gills) * Conjoined twins Conjoined twins – sometimes popularly referred to as Siamese twins – are ...

or slightly

decurrent ''Decurrent'' (sometimes decurring) is a term used in botany and mycology to describe plant or fungal parts that extend downward. In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petio ...

. The pores are also yellow and quite large, up to 2.5 mm in diameter each and angular in shape. The

spores In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

are generally spindle-shaped to oval and have a smooth or striate surface. The

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

is brown or slightly olive-tinged when fresh. Morphological Features of Xerocomoid Boletes

Ecology

''Xerocomellus'' species form mycorrhizal associations with coniferous and

deciduous tree In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

Species

References

External links

* * {{Taxonbar, from=Q1230774 Boletaceae Boletales genera