it can produce literally a bitter disappointment to the mushroom hunter. The rule of thumb is that the bitter bolete has pink pores, and a brownish stipe with a dark brown (sometimes approaching black) reticulum, while the cep has whitish pores, which in maturity become yellowish or sometimes with a faint olivaceous tint, a light-colored (white and/or similar in color to the rest of the stipe) reticulum and white hyphae tufts at the base of the stipe. The bitter bolete also lacks the stuffed or plugged pore appearance (caused by a hyphal mat of cheilocystidia) that is common in the cep and its allies. If uncertain, tasting a small piece of cap context should clinch the identification, since Tylopilus felleus has a strong, foul bitter taste. Toxicity Rubroboletus satanas has long been considered to be poisonous, though it is not known to have been responsible for any fatalities and the symptoms are predominantly gastrointestinal in nature. A glycoprotein, bolesatine, is thought to be responsible for the poisonings. When given to mice, Bolesatine causes massive thrombosis, while at lower concentrations it is a mitogen, inducing cell division to human T lymphocytes. A similar compound, bolevenine, has been isolated from the poisonous Neoboletus venenatus in Japan. More recent studies have associated the poisoning caused by R. satanas with hyperprocalcitonemia, and classified it as a distinct syndrome among fungal poisonings. Several other boletes are known to cause varying degrees of gastrointestinal symptoms, especially if eaten raw or insufficiently cooked. One incident of death associated with Rubroboletus pulcherrimus was reported in 1994; a couple developed gastrointestinal symptoms after eating this fungus, with the husband finally succumbing. An autopsy revealed infarction of the midgut. See also Bolete eater List of North American boletes References Cited texts External links Basidiomycota families Taxa named by François Fulgis Chevallier Taxa described in 1826