TYLOPILUS PSEUDOSCABER (Secretan) Smith and Thiers, Boletes of Michigan, p.96. 1971
Boletus pseudoscaber Secretan, Mycogr. Suisse 3:13. 1833.
Porphyrellus pseudoscaber (Secretan) Singer, Farlowia 2:115. 1945.
Boletus olivaceobrunneus Zeller and Bailey, Mycologia 27:457. 1935.
Porphyrellus atrofuscus Dick and Snell, Mycologia 52:449. 1960.
Illustrations: See Microfiche No. 54
Singer, R., Die Rohrlinge, Teil 11, pl. XXVI, figs. 4-9.
Smith, A. H., and H. D. Thiers, The Boletes of Michigan, pl. 47.

Pileus 6-15 cm broad at maturity, convex to broadly convex when young, becoming plano-convex to irregular with an undulating to uneven margin with age; surface dull, unpolished, velutinous to tomentose during all stages of development, smooth, rarely finely areolate and fibrillose-scaly; color sooty black to very dark brown ("clove brown" to "fuscous" to "mummy brown"), occasionally slightly darker on the disc and paler on the margin, black when dried; margin entire, incurved to decurved. Context 1-2 cm thick, white, slowly staining weakly blue in some areas, pink ("testaceous") in other areas, blue discoloration slowly disappearing and becoming pink ("testaceous"), staining wax paper dark blue green. Taste not distinctive; odor often strong and pungent.

Tubes 1.5-2 cm long, shorter toward the margin, deeply and broadly to narrowly depressed, dark brown to almost black ("cinnamon-drab" to "drab" to "benzo brown"), slightly paler on the margin, staining blue at first when bruised, then changing to purplish brown ("deep brownish drab" to "dusky drab"); pores up to 1 mm wide with occasional larger pores irregularly distributed, angular, concolorous with the tubes, frequently bluing and then changing to dark mahogany brown when bruised.

Stipe 13-20 cm long, 1.5-2 cm thick at the apex, clavate to subclavate, solid to stuffed; surface dry, dull, glabrous, longitudinally ridged and often somewhat reticulate, dark brown ("bone brown" to "clove brown"), staining reddish vinaceous when first bruised, eventually becoming dark brown to black, occasionally scattered areas staining blue, whitish at the base. Context pale pinkish tan ("pale pinkish buff"), becoming pale flesh color ("testaceous") when exposed.

Spore print deep reddish brown. Spores 13.8-17.6 X 6-9.6 Ám, dark ochraceous in Melzer's, pale yellow in KOH, smooth, thick-walled, subfusoid to subcylindric to subovoid in face view, inequilateral in side view, no apical pore.

Basidia 30-45 X 10-15 Ám, clavate, four-spored, hyaline; irregular areas in hymenium staining dark brown in KOH. Hymenial cystidia 36-51 X I2-15 Ám, abundant, cinnamon brown in KOH, chocolate brown in Melzer's, embedded in the hymenium, fusoid-ventricose to mucronate to clavate with elongated, tapering apices.

Tube trama divergent, hyaline, appearing somewhat gelatinous in KOH, hyphae ▒8 um wide. Pileus trama interwoven, hyaline except for scattered areas that stain brown in KOH, homogeneous. Pileus cuticle differentiated as a trichodermium, which frequently collapses with age, with scattered free hyphal tips colored cinnamon brown in KOH, not incrusted, contents of cells staining brown in KOH, hyphae up to 10 Ám wide. Stipe cuticle differentiated as a tangled trichodermium that stains cinnamon brown in KOH. Clamp connections absent.

Chemical reactions KOH-cuticle dark red, context red; HN03, HCL, and H2SO4-context pink, cuticle bright red; sulfoformalin-context and cuticle red; FeS04-cuticle dark gray.

Habit, habitat, and distribution Scattered in the mixed coastal forests of northern California. It is often found growing on well-decomposed Sitka spruce logs and stumps, but has also been found in humus under Sitka spruce and various pines. Fruiting during the fall and winter season. Usually much more abundant in the area north of Eureka than elsewhere in the state.

Material studied Del Norte County: Thiers 17760. Humboldt County: Sundberg 977; Thiers 14248, 14355, 14417, 14443, 17642, 21222, 21389, 21462, 21484, 22889, 22904, 26883; White 508. Mendocino County: Orr 846.

Observations This very distinctive bolete is easily recognized by the dull-black color of the entire basidiocarp except for the basal portion of the stipe, which is often whitish. In addition, the context, at least in part, shows a blue discoloration when exposed, and in most instances wax paper will be stained blue to blue green when in contact with the basidiocarps. It is closely related to T. porphyrosporus, which has pores that are pallid to grayish in color and a context that does not change to blue when exposed. Tylopilus pseudoscaber has frequently been misidentified on the west coast and has been the basis for the publication of at least two new species. Zeller and Bailey made collections of it in Oregon and described them as new under the name of Boletus olivaceobrunneus. Several years later Dick and Snell, studying basidiocarps from the vicinity of San Francisco, described them as new under the name of Porphyrellus atrofuscus. The type material of both of these species has been examined and no significant differences from T. pseudoscaber could be found.

Edibility unknown.

Online edition addendum

Other Descriptions and Photos: The Fungi of California

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
A MykoWeb Page