Xerocomellus cisalpinus
Description
Cap up to 10 cm, at first hemispherical then convex, ochraceous, pale brown, grayish brown, olivaceous brown, dark brown to blackish brown, sometimes with a reddish tint or entirely red, dry, velvety but very soon cracking and pinkish flesh is revealed in the cracks. Stipe cylindrical to slightly club-shaped, often curved and usually tapering at the base, bright yellow in the upper half, downwards gradually becoming bright red, blueing when bruised. Flesh cream to yellowish in the cap, brownish in the stipe, blueing when exposed to air, most notably in the stipe.
Xerocomellus cisalpinus is habitat in deciduous forests, mycorrhizal mostly with oaks (Quercus), but also with beech (Fagus), pines (Pinus), part of the British records also with cedar (Cedrus).
It is considered edible only if it is cooked thoroughly; however, it lacks both texture and flavor and so it is not rated by any but the most ravenously hungry of fungiphages.
Common names: Bluefoot Bolete.
Mushroom Identification
Cap
It has a shallow, convex gray-yellow or brownish cap that soon crazes to reveal a thin layer of red flesh below the skin. 4 to 10cm in diameter when fully expanded, the caps have very little substance and the thin flesh blues very slightly when cut. Young specimens can have dark downy caps and might be mistaken for Bay Boletes, Boletus badius.
Tubes
The tubes are yellow and usually turn slowly blue-green when cut.
Pores
The yellow tubes terminate in large, angular pores that are lemon yellow at first but turn greenish with age. When bruised, the pores of mature specimens sometimes turn greenish-blue.
Stem
The stem has no ring, is bright yellow and the lower part is covered in coral-red fibrils. When cut or bruised, over a few minutes the cream stem flesh turns blue-green near the base of the stem, where there is often a region of purplish-red stained flesh within the stem. 10 to 15mm in diameter and 4.5 to 8cm tall, the stem is more or less constant in diameter throughout its length or slightly broader at the apex. Sometimes the stem base is slightly bulbous.
Spores
Subfusiform, 11.5-14.5 x 4.3-6.8µm; very finely lined.
Spore Print
Olivaceous brown.
Odor and Taste
Not distinctive.
Habitat & Ecological Role
This ectomycorrhizal species is particularly common in conifer forests, notably with spruces, but it also occurs under deciduous trees in woods and parks.
Xerocomellus cisalpinus Look-Alikes
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Similar although reportedly less prone to cracking and displaying red sub-cuticle flesh; its stem base does not turn noticeably blue when cut or bruised, and its spores are not minutely striated as those of Boletus cisalpinus are.
Pseudoboletus parasiticus (synonyms Xerocomus parasiticus and Boletus parasiticus)
Has a yellow stem without red fibrils, and it occurs only with the Common Earthball (Scleroderma citrinum) upon which it may be slightly parasitic.
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Also has striate spores very rarely has cracked cap surface. In addition the spores of X. cisalpinus are somewhat smaller (usually less than 5 μm wide) than in the two species above.
History
This 'relatively new' species was first described in 2003 by Simonini, H. Ladurner & Peintner, who gave it the name Xerocomus cisalpinus. The name Xerocomellus cisalpinus is now more generally accepted and dates from a 2011 publication by German mycologist Wolfgang Klofac.
The generic name Boletus comes from the Greek bolos, meaning 'lump of clay', while the new genus name Xerocomellus indicates a (rather distant, actually) relationship with the genus Xerocomus. The prefix Xero- means dry.
The specific epithet cisalpinus is Latin and translates as 'lying on this (meaning the Roman) side of the Alps'.
Photo sources:
Photo 1 - Author: Lukas from London, England (CC BY-SA 2.0)
Photo 2 - Author: Lukas from London, England (CC BY-SA 2.0)
Photo 3 - Author: Lukas from London, England (CC BY-SA 2.0)
Photo 4 - Author: Lukas from London, England (CC BY-SA 2.0)
