Rubroboletus lupinus
Description
Rubroboletus lupinus is a bolete fungus of the genus Rubroboletus. It has a big cap up to 15 cm and is initially whitish, pale grey or very pale ochraceous and tinted red at the cap margin. It is a choice edible mushroom.
This mushroom habitat in warm broadleaf forests, mycorrhizal with oaks (Quercus) and sweet chestnut (Castanea).
Rubroboletus lupinus is southern species, that is more common in the Mediterranean area and is absent in Northern Europe.
Molecular studies have revealed considerable genetic variation among European populations of R. lupinus, placing it in a clade sister to Rubroboletus dupainii. The species is found in warm broad-leaved forests, forming ectomycorrhizal associations with various species of oak (Quercus) and sweet chestnut (Castanea).
Fruitbodies with red caps may resemble Boletus dupainii, but the later has numerous fine red dots allover the stipe surface, while the stipe in B. lupinus is mostly yellow. Boletus queletii may probably sometimes look similar, but it has vinaceous flesh in the stipe base and amyloid hyphae.
Common names: Wolf Bolete.
Mushroom Identification
Cap
Pileus up to 15 cm, convex to flat-convex or almost flat, dry, smooth, initially whitish, pale grey or very pale ochraceous and tinted red at the cap margin, later with strongly developing pinkish tint, finally almost entirely pale pink, pink, dark pink or reddish-pink, often spotted darker.
Stipe
Club-shaped, cylindrical, or bulbously swollen, often tapering towards the base, almost entirely pale or bright yellow, discoloring to yellowish, often tinted orange-red or reddish in places, in the upper part covered with very fine yellow granules, downwards almost smooth.
Flesh
Lemon yellow, blueing when exposed to air. Tubes lemon yellow to yellow with olivaceous tint, blueing when injured. Pores red or orange-red, blueing when bruised.
Odor and Taste
Not distinctive.
Spores
11–15 × 5–6 μm, ratio 2–2.5.
Pileipellis (the cap cuticle)
A trichodermium of interwoven septate hyphae of cylindrical, finely incrusted cells.
Chemical reactions
Hyphae of the flesh in the stipe base inamyloid with Melzer’s reagent.
History
Originally described by Elias Magnus Fries in 1838 as species of Boletus, it was transferred to Rubroboletus in 2015, a genus circumscribed to host other allied reddish-colored, blue-staining bolete species forming a distinct clade.
The species epithet is derived from the Latin word lupus, meaning "wolf".
Photo sources:
Photo 1 - Author: Alessandro Scotti (CC BY-SA 3.0)
Photo 2 - Author: Davide Puddu (Davide Puddu) (CC BY-SA 3.0)
Photo 3 - Author: Alessandro Scotti (CC BY-SA 3.0)
Photo 4 - Author: Bernypisa (CC BY-SA 3.0)