Rubroboletus satanas

Description
Mushroom Identification
Look-Alikes
History
Synonyms

Description

Rubroboletus satanas is a deadly poisonous basidiomycete fungus of the bolete family (Boletaceae) and one of its most infamous members. Found in broad-leaved and mixed woodland in the warmer regions of Europe, it is classified as a poisonous mushroom, known to cause gastrointestinal symptoms of diarrhea and violent vomiting. However, reports of poisoning are rare, due to its striking appearance and at times putrid smell, which discourage casual experimentation.

The squat, brightly colored fruiting bodies are often massive and imposing, with a pale, dull-colored velvety cap, yellow to orange-red pores, and a bulbous red-patterned stem. The flesh turns blue when cut or bruised and overripe fruitbodies often emit an unpleasant smell reminiscent of carrion. It is arguably the largest bolete found in Europe.

It was known as Boletus satanas before its transfer to the new genus Rubroboletus in 2014, based on molecular phylogenetic data.

In the southern regions of France during the summer of 2011, 184 cases of Devil’s bolete poisoning were called into Poison Control. In a study of 58 cases seen in an emergency department over 7 days, the wild mushroom eaters experienced abdominal pain (40%), diarrhea (67%), and vomiting (73%), with 45 of the patients hospitalized. All of the afflicted individuals experienced gastrointestinal distress several hours after eating Devil’s bolete, but recovered quickly after supportive care and intravenous fluids.

Common names: Satan's Bolete, Devil's Bolete.

Mushroom Identification

Cap

10-22 cm in diameter, convex, becoming broadly convex; pale grey to pale olive-buff, pinkish tones sometimes developing in age particularly along the margin, occasionally aereolate near the disc; flesh olive-buff, thick, bruising blue; odor and taste undistinguished.
Hymenophore

Pores fine, dark red, fading in age to reddish-orange, bruising blue.
Stipe

7-14 cm tall, base abruptly bulbous, up to 13+cm broad, narrowing to 4-7 cm at the apex; pink to vinaceous reticulations above, pale pinkish tones below, fading in age; flesh same as the cap, bruising blue.
Spores

Spores 11-15 x 3.5-6 µm, elliptical, smooth.
Spore Print

Olive-brown.
Habitat

Solitary to scattered under oaks, especially Quercus agrifolia (coast live oak); from late fall to early winter; common in some years, rare in others.

Look-Alikes

Suillellus luridus

Has a darker cap and orange flesh in the stem base; it blues instantly when cut.
Caloboletus calopus

Has a pale cap but its pores are yellow rather than red.
Rubroboletus rhodoxanthus

Found predominantly on acidic soil, develops pinkish tinges of the cap, has a more or less cylindrical or clavate stipe with a very dense, well-developed net and lemon-yellow flesh that distinctly stains blue only in the cap when longitudinally sliced.
Rubroboletus legaliae

Acidophilous, has pinkish tinges on the cap, flesh that stains more extensively blue when cut, and narrower spores, measuring 9–15 × 4–6 μm.
Rubroboletus pulchrotinctus

Has a variable cap color often featuring a pinkish band at the margin, has a dull-colored stipe without deep red tinges, pores that remain yellow or orange even in mature fruit bodies, and somewhat narrower spores, measuring 12–15 × 4.5–6 μm.
Rubroboletus rubrosanguineus

Associated with spruce (Picea) or fir (Abies), has pinkish tinges on the cap and smaller spores, measuring 10–14.5 × 4–6 μm.
Caloboletus calopus

Usually associated with coniferous trees, has pores that remain persistently yellow even in overripe fruit bodies, has a more slender, cylindrical or clavate stipe, and narrower spores, measuring 11–16 × 4–5.5 μm.

History

Originally known as Boletus satanas, the Satan's bolete was described by German mycologist Harald Othmar Lenz in 1831. Lenz was aware of several reports of adverse reactions from people who had consumed this fungus and felt himself ill from its "emanations" while describing it, hence giving it its sinister epithet.

The Greek word σατανᾶς (satanas, meaning Satan), is derived from the Hebrew śāṭān (שטן). American mycologist Harry D. Thiers concluded that material from North America matches the species description, however, genetic testing has since confirmed that the western North American collections represent Rubroboletus eastwoodiae, a different species.

Genetic analysis published in 2013 revealed that B. satanas and several other red-pored boletes, are part of the "dupainii" clade (named after B. dupainii), and are distantly nested from the core group of Boletus (including B. edulis and relatives) within the Boletineae. This indicated that B. satanas and its relatives belonged to a distinct genus.

The species was hence transferred to the new genus Rubroboletus in 2014, along with several allied red-pored, blue-staining bolete species. Genetic testing on several species of the genus revealed that R. satanas is most closely related to R. pulchrotinctus, a morphologically similar but much rarer species occurring in the Mediterranean region.