Arora, D. (2008). California Porcini: Three new taxa, observations on their harvest, and the tragedy of no commons. Economic Botany 62: 356-375.

Pileus tipice juventute atrobrunneus subter tunica tenui, alba, pruinosa, pallescens vel magis cinnamo- mescens et viscidescens. Pagina pori juventute alba, lutescens tum viridi-flavescens. Stipes crassus, vulgo albus, ad partem superam reticulatus. Contextus crassus, albus, ubi incisus immutabilis. Sporae 12-15 × 4-4.6 μm. Pileipellis maturitate cutis omnino gelatinosa. Typus hic designatus Arora 7202 (SFSU), Casa Madera, Gualala, CA.

Pileus (cap) 7–30 cm broad, at first convex, then broadly convex to nearly plane; color very dark brown when fresh but often entirely or partially overlaid with a fine white bloom that gives it a paler, frosted appearance, in age the hoary patches tending to disappear and the surface often becoming paler brown or cinnamon blotched with even paler (white to pale tan) areas; surface glabrous except for the hoary patches, moist at first but typically becoming viscid in age or wet weather, sometimes uneven or with broad depressions. Pore surface and tube layer white when young, becom- ing yellow, then greenish-yellow as it matures; not blueing when bruised. Stipe 2.5–8 cm thick, 7– 20 cm long, equal to clavate or slightly bulbous (usually more bulbous when young); surface finely reticulate over at least the upper portion, the reticulation white at first, white or brown in age; surface otherwise glabrous and white or nearly so, sometimes becoming brownish in age but more often remaining white. Context thick and white in both the cap and stalk (but sometimes vinaceous- tinged when young), not staining appreciably when cut or sometimes exhibiting a very slight blueing just above the tube layer; odor and taste mild.

Spores olive-brown in mass, but yellower than closely related species under the microscope, variable in shape and dimensions, long ellip- soid-fusiform, (11.5) 12–15 (17)×(3.9) 4–4.7 (5.4) μm; Q = (2.5) 2.8–3.3 (4.2), n = 30. Basidia clavate, hyaline, mostly 4-spored, 23–40 × 8– 11.5 μm. Hymenial cystidia thin-walled, inconspicuous. Pileipellis a completely gelatinized cutis when mature (and sometimes even in youth), typically 200–250 μm thick. Cuticular cells 7–10 μm wide, variable in shape, sometimes branched or with diverticula.