Pileus 7-10 cm latus, siccus, areolatus, tomentosus, fuscus, non rufus in fissuris. Contextus 1-1.5 cm crassus, alutaceus tactu immutabilis vel tarde caerulescens. Sapor et odor mitis. Tubuli 1 cm longi, flavi, tactu caerulei; pori 1-2 mm lati, rufi tactu caerulei. Stipes 10-11 cm longus, 1-1.5 cm crassus, siccus, appresso-fibrillosus, brunneus. Sporae 15-21 X 4-5 Ám, anguste cylindricae. Cystidia 30-40 X 8-12 Ám, conferta vel dispersa, clavata, apice elongata attenuata. Cuticulae hyphis intertextis et incrustatis composita. Holotypus (no. 18392) a H. D. Thiers lectus proper Jackson State Forest, Mendocino County, January 8, 1967; in Herbarium San Franciso State University conservatus.

Pileus 7-10 cm broad, convex when young, becoming plano-convex to plane with a flared or somewhat uplifted margin; surface dry, noticeably areolate, especially toward the disc, areoles small, tomentose to velutinous during all stages of development; color dark brown ("Saccardo's umber" to "snuff brown") to occasionally blackish brown ("fuscous" to "sepia" to "bister"), no reddish color apparent in the flesh exposed in the cracks on the pileus; margin entire, becoming somewhat rimose with age. Context 1-1.5 cm thick, tan ("warm buff" to "pale olive-buff"), unchanging or slowly changing to blue upon exposure. Taste, and odor mild.

Tubes 1 cm in length, somewhat depressed, becoming subdecurrent, yellow ("reed yellow" to "old gold"), bluing when bruised or exposed; pores 1-2 mm broad, angular, red ("jasper red" to "dragons-blood red"), bluing when bruised.

Stipe 10-11 cm long, 1-1.5 cm thick at the apex, equal, solid to stuffed; surface dry, finely appressed-fibrillose to obscurely fibrillose-scaly; color brown ("cinnamon-brown" to "tawny-olive" to "sayal brown"), often with a reddish cast at the apex and base, brown color due primarily to the fibrillose covering, ground color pale yellow, yellow mycelium at the base. Context yellow at the base and apex, reddish in midportion, changing to blue when exposed.

Spore print color unknown. Spores 15-21(27) X 4-5(6) Ám, narrowly cylindric in face view, slightly inequilateral in profile, giant spores and pleomorphism rather common, ochraceous in Melzer's (not dextrinoid), pale ochraceous in KOH; walls smooth, thin.

Basidia 24-29 X 7-9 µm, clavate, hyaline, four spored. Hymenial cystidia 30-40 X 8-12 Ám, crowded on pores, scattered elsewhere, hyaline, thin-walled, clavate, apex often elongated or tapering.

Tube trama hyaline in KOH, obscurely divergent, hyphae 4-6 Ám wide., Pileus trama homogeneous, interwoven. Pileus cuticle dark brown ("chestnut brown") in KOH, differentiated as a trichodermium of tangled hyphae with the terminal cell slightly enlarged, heavily incrusted but not spirally so. Stipe cuticle similar to that of the pileus. Clamp connections absent.

Chemical reactions unknown.

Habit, habitat, and distribution Solitary in dense hardwood-conifer forest. Until recently known only from the coast near Mendocino.

Material studied Mendocino County: Thiers 18392 type. Trinity County: Thiers 30659.

Observations This species obviously is in the B. chrysenteron complex, but is readily distinct because of the absence of any red pigment in the cracks on the pileus, the presence of the red pores, and the large spores. The absence of any amyloid reaction or truncate apex in the spores readily distinguishes it from B. truncatus and related species.

Edibility undetermined.

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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