Cap 9-17 cm broad, convex, expanding to broadly convex; margin incurved when young, then decurved, often wavy, overlapping the pore surface; surface dry, uneven or pitted, matted-tomentose, at maturity occasionally appressed fibrillose-squamulose, in dry weather patchy-areolate; color: dull-brown to cream-brown, the pigments often mottled, frequently tinged reddish towards the margin; context cream-yellow, 3.0-4.0 cm thick at maturity, soft, bluing when cut, sometimes erratically, larval tunnels vinaceous; odor not distinctive; taste mild.
Pores dull red, shading to reddish-orange at the margin, in age reddish-brown, when young, 2-3 per mm, 1-2 per mm at maturity, bluing when bruised; tubes up to 1.0 cm long, dull yellow-green, bluing when injured, adnate in youth, eventually depressed at the stipe.
Stipe 7.0-14.0 cm long, up to 8.0 cm thick at the base, clavate, gradually narrowing toward the apex; upper two-thirds of stipe covered with vinaceous-red reticulations over a pallid background, bruising blue, the stipe base dingy-buff, matted-tomentose, becoming blackish-brown where handled; context firm, fleshy, cream-yellow, sometimes pale-vinaceous at the base, the upper portion bluing when cut or injured, worm holes edged vinaceous.
Spores 13.0-15.5 x 5.0-6 µm, smooth, moderately thick-walled, narrowly ellipsoid in face-view, spindle-shaped in profile; hilar appendage inconspicuous; spore print brown to dull olive-brown.
Solitary to scattered in mixed hardwood/conifer woods; known from coastal forests north of San Francisco; fruiting from late fall to early winter.
This red-pored bolete is recognized by its large size and club-shaped stipe with coarse, reddish reticulations. In coastal California, only Boletus eastwoodiae is similar, but it can be distinguished by an abruptly bulbous stipe, and a short, squat stature. Microscopically, these two species are also distinct, the spores of Boletus pulcherrimus averaging several microns longer than those of B. satanas. Two other red-pored boletes that occur in the Bay Area are Boletus amygdalinus and Boletus erythropus. They are differentiated from B. pulcherrimus by smaller size and nonreticulate stipes. Boletus pulcherrimus was known for many years as B. eastwoodiae, a name which became invalid for this species when a study of the type collection proved it to be a specimen of what we had been calling B. satanas.