Rubinoboletus rubinus
Description
Rubinoboletus rubinus is an ectomycorrhizal small but conspicuous bolete that is known in the central and south regions of Europe and European Russia. It is very rare throughout its distribution, including in the Red Lists of seven countries and Red Data Book of Russian Federation as well. This thermophilous species inhabits open broadleaved forests with old oak trees mostly in the floodplain communities or parklands of the river valley, where it forms mycorrhiza with Quercus.
Rubinoboletus rubinus is similar and might be confused with Chalciporus amarellus. The latter however has different cap color, ellipsoid spores and grows under conifers.
Common names: Crimson Bolete.
Mushroom Identification
Cap
3 to 8 cm across, initially hemispherical and eventually becoming almost flat; smooth or slightly tomentose; dry, often becoming slightly sticky or greasy in wet weather; yellowish orange to reddish-brown. The cap flesh is yellow with a pinkish region immediately beneath the cap cuticle. A tangled trichodermium of broad (typically 15µm diameter) hyphae.
Tubes and Pores
The shortly-decurrent ochre tubes become pinker towards their termination in irregularly angular carmine pores that do not change color significantly when bruised.
Stem
2 to 5cm tall and 0.5 to 1.5cm in diameter; surface bright carmine; cylindrical, usually tapering in slightly towards a yellowish base. Stem flesh whitish near cap, becoming bright yellow towards the base.
Spores
Broadly ellipsoidal, smooth, 5.5-8.5 x 4-5.5µm.
Spore Print
Pale reddish-brown to ochre.
Odor and Taste
Odor pleasant but not distinctive; taste mild (distinguishing it from Chalciporus piperatus whose spores are hot and very peppery).
Habitat & Ecological Role
Mycorrhizal, found in oak woodland as well as under Beech in Britain but also recorded under Hornbeam trees in some parts of mainland Europe.
History
This species was originally named and described in 1868 by English mycologist Worthington George Smith (1835-1917) who gave it the binomial scientific name Chalciporus rubinus. Some authorities still hold this to be the most appropriate name; however, the name used here, Rubinoboletus rubinus, reflects the fact that in microscopic details this bolete is very different from Chalciporus species.
The name Rubinoboletus rubinus dates from a 1969 publication by Czech mycologist Albert Pilàt (1903-1974) and Slovak mycologist Aurel Dermek (1925-1989).
Synonyms of Rubinoboletus rubinus include Boletus rubinus W.G. Sm., Chalciporus rubinus (W.G. Sm.) Singer, Suillus rubinus (W.G. Sm.) Kuntze, and Xerocomus rubinus (W.G. Sm.) A. Pearson.
The generic name Boletus comes from the Greek bolos, meaning 'lump of clay', while the specific epithet rubinus comes from Latin and refers to the ruby-red coloring of pores and stem.
Photo sources:
Photo 1 - Author: Xth-Floor (CC BY-SA 3.0)
Photo 2 - Author: Strobilomyces (CC BY-SA 2.5)
Photo 3 - Author: Xth-Floor (CC BY-SA 3.0)
Photo 4 - Author: Xth-Floor (CC BY-SA 3.0)
