Pileus 2-4 cm latus, siccus, velutinus demum glaber, coccyginus. Contextus flavus tactu immutabilis vel tarde caeruleus. Sapor et odor mitis. Tubuli 2-5 mm longi, sordide flavi, immutabiles; pori concolores, immutabiles. Stipes 1.5-4.5 cm longus, 0.5-1 cm crassus, siccus, appresso-fibrillosus demum glaber, laevis, rufus; contextus flavus, immutabilis. Sporae 11.2-17.6 X 5.3-7 Ám, amyloideae, cylindricae, laeves. Cystidia absentia. Cuticula intertexta. Holotypus (no. 21237) a Wm. Jordan lectus prope Big Meadow Campground, Alpine County, October 14, 1967; in Herbarium San Francisco State University conservatus.

Pileus 2-4 cm broad at maturity, convex when young, becoming broadly convex to plane to irregularly lobed, incised or convoluted at maturity; surface dry to moist but not viscid, typically finely velutinous to covered with a fine red pubescence when young, usually becoming glabrous with age, plush-like in appearance, sometimes finely areolate near the margin, more or less evenly colored purple red ("Corinthian red" to "dark vinaceous" to "deep Corinthian red"), sometimes slightly paler ("orange-vinaceous" to "Etruscan red"), unchanging or becoming slightly paler with age; margin entire, decurved. Context 0.5-1 cm thick, yellow ("maize yellow" to "baryta yellow"), usually unchanging, but sometimes slowly and erratically changing to blue. Taste mild; odor not distinctive.

Tubes 2-5 mm long, adnate to depressed, seceding from stipe, dull yellow ("old gold" to "colonial buff"), unchanging when exposed; pores 0.3-1 mm broad, angular, bright yellow ("amber yellow"), unchanging when bruised.

Stipe 1.5-4.5 cm long, 0.5-1 cm thick at apex, equal to tapering downward, light-yellow mycelium at base, stuffed to solid; surface dry, appressed fibrillose becoming glabrous, smooth or with longitudinal striations, not reticulate; color red ("Corinthian red" to "Etruscan red"), yellowish at the base. Context yellow, unchanging when exposed.

Spore print olive brown. Spores 11.2-17.6 X 5.3-7 Ám, ochraceous in KOH, often dextrinoid, cylindric, to ovoid to ellipsoid, highly variable in size and shape, pleomorphic, smooth, moderately thick-walled.

Basidia 23-28 X 7-10 Ám, apparently one-, two-, three-, and four-spored, clavate, hyaline in KOH. Hymenial cystidia not apparent, but occasional basidioid cells staining dark brown in Melzer's scattered in hymenium.

Tube trama divergent, hyaline in KOH, hyphae up to 6 Ám wide. Pileus trama closely interwoven, pale ochraceous in KOH, homogeneous. Pileus cuticle differentiated as a tangled trichodermium of more or less repent hyphae 5-7 Ám wide, staining dark yellow in KOH, ochraceous in Melzer's, walls asperulate to faintly incrusted. Clamp connections absent.

Chemical reactions unknown.

Habit, habitat, and distribution Gregarious to subcespitose in soil in conifer forests. This fungus is apparently rare and is known from only three collections from California plus a few from the Pacific Northwest. In California it is curious to note that, even though known from only three collections, it has been found in the coastal and mountainous regions.

Material studied Calaveras County: Thiers 21237 (collection made by William Jordan) type. San Francisco County: Orr 919. San Mateo County: Orr 860.

Observations Boletus coccyginus apparently belongs in the section Subtomentosi, but does not fit well into any subsection recognized within that section. Except for the fact that the pores do not stain blue when bruised, it would seem to belong in the subsection Fraterni, where it is tentatively placed. It appears most closely related to B. campestris, which has pores that turn blue when bruised, noticeable cystidia, and a pileus that is ferrugineous rather than rose red when dried. Boletus campestris occurs in a different type of habitat and is not known from California.

Boletus coccyginus is very distinct and is not likely to be confused with any other California bolete. It is characterized by the rose-colored pileus, small pores that do not change to blue when bruised, no highly differentiated cystidia, and pleomorphic (variable) spores.

Edibility undetermined, but its small size makes it insignificant for culinary purposes.

The Boletes of California
Copyright © 1975 by Dr. Harry D. Thiers
Additional content for the online edition © 1998 by Michael Wood, Fred Stevens, & Michael Boom
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