Rubroboletus satanas

Originally known as Boletus satanas, 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 apparently felt himself ill from its "emanations" while describing it, hence giving it its sinister epithet. The Greek word (satanas, or Satan) is derived from Hebrew śāṭān (שטן). however, genetic testing has since confirmed that 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. ==Description==

The compact cap can reach an impressive , exceptionally , and very rarely in diameter. It is arguably the largest bolete found in Europe. At first it is hemispherical with an inrolled margin, but becomes convex at maturity as the fruit body expands, while in older specimens the margin might be slightly undulating. When young, the pileus is greyish white to silvery-white or buff, but older specimens tend to develop olivaceous, ochraceous or brownish tinges. The surface of the cap is finely tomentose, becoming smooth at maturity and is often slightly viscid in wet weather. The cuticle is tightly attached to the flesh and does not peel. The spore print is olivaceous green. The spores are fusiform (spindle-shaped) when viewed under a microscope and measure 10–16 × 4.5–7.5 μm. The cap cuticle is composed of interwoven septate hyphae, which are often finely incrusted. Similar species Satan's bolete can be confused with a number of other species: • Rubroboletus rhodoxanthus is 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 is also 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 colour often featuring a pinkish band at the margin; has a dull-coloured 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 is 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 is 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. ==Distribution and habitat==

Rubroboletus satanas is widely distributed throughout the temperate zone, but is rare in most of its reported localities. In Europe, it mostly occurs in the southern regions and is rare or absent in northern countries. It fruits in the summer and early autumn in warm, broad-leaved and mixed forests, forming ectomycorrhizal associations with oak (Quercus) and sweet chestnut (Castanea), with a preference for calcareous (chalky) soils. Other frequently reported hosts are hornbeam (Carpinus), beech (Fagus) and lime and linden trees (Tilia). It is rare in Scandinavia, occurring primarily on a few islands in the Baltic Sea where conditions are favourable, with highly calcareous soil. as well as Crimea and Ukraine, with its distribution possibly extending as far south as Iran. but these sightings are instead of the closely related species Rubroboletus eastwoodiae. ==Toxicity==

This mushroom is moderately poisonous, especially if eaten raw. The symptoms, which are predominantly gastrointestinal in nature, include nausea, abdominal pain, and violent vomiting with bloody diarrhea that can last up to six hours. The toxic enzyme bolesatine has been isolated from fruiting bodies of R. satanas and is implicated in the poisonings. Bolesatine is a protein synthesis inhibitor and, when given to mice, causes massive thrombosis. At lower concentrations, bolesatine is a mitogen, inducing cell division in human T lymphocytes. Muscarine has also been isolated from this fungus, but the quantities are believed to be far too small to cause toxic effects in humans. and classified it as a distinct syndrome among fungal poisonings. Controversially, English mycologist John Ramsbottom reported in 1953 that R. satanas is consumed in certain parts of Italy and the former Czechoslovakia. In those regions, the fungus is reportedly eaten following prolonged boiling that may neutralise the toxins, though this has never been proven scientifically. Similar reports exist from the San Francisco Bay Area of the United States, but probably involve a different fungus misidentified as R. satanas. Ramsbottom speculated that there may be a regional variation in its toxicity, and conceded that the fungus may not be as poisonous as widely reported. Nevertheless, R. satanas is rarely sampled casually, not least because of the foul smell, which in addition to their bright red colour and blue staining, make this fungus unappealing for human consumption. ==References==