BOLETUS AMYGDALINUS (Thiers) Thiers, nomen nov.
Boletus puniceus Thiers, Mycologia 57:529. 1965.
Illustrations: See Microfiche No. 2

Pileus 6-10 cm broad at maturity, convex when young, becoming plano-convex to plane with age, often highly irregular or undulating; surface dry, matted tomentose to cottony fibrillose to appressed fibrillose, usually not appearing fibrillose scaly or rimose; typically colored dark rose to red ("ocher red" to "Etruscan red" to "Corinthian pink") when young, unchanging or changing to dark brownish red ("brownish vinaceous" to "light russet-vinaceous" to "russet" to "vinaceous-russet" to "terra cotta") on the disc when older, sometimes changing to reddish brown ("vinaceous-brown" to "sorghum brown") toward the margin; margin incurved becoming decurved, entire. Context 1-2 cm thick, yellow ("naphthalene yellow" to "amber yellow"), bluing immediately upon exposure. Taste and odor not distinctive.

Tubes 1-1.5 cm long, shallowly to deeply depressed, dark yellow ("olive lake" to "pale greenish yellow" to "naphthalene yellow"), bluing upon exposure; pores 0.5-1 mm broad, angular, red ("ox-blood red" to "dragons-blood red" to "ferruginous" to "vinaceous-rufous"), bluing immediately upon bruising.

Stipe 5-9 cm long, 1-3 cm thick at the apex, typically bent near the base, equal to ventricose, solid; surface dry to moist, glabrous at the apex, typically becoming tomentose to granulose toward the base, not reticulate; color yellow ("naphthalene yellow" to "massicot yellow"), usually masked with red ("pompeian red" to "dragons-blood red" to "brick red") granules or tomentum, bluing when bruised. Context yellow, becoming dark blue immediately upon exposure.

Spore print dark olive brown. Spores 11.2-16 X 5.2-8 Ám, ochraceous in KOH, dark ochraceous in Melzer's, ellipsoid to subfusoid, thick-walled, smooth, frequently appearing two-celled because of two distinct vacuoles.

Basidia 30-35 X 9-11 Ám, clavate, four-spored, guttulate. Hymenial cystidia 45-54 X 10-12 Ám, scattered, hyaline, fusoid to fusoid-ventricose with tapering apices, relatively obscure, sometimes appearing incrusted.

Tube trama hyaline, obscurely divergent to parallel. Pileus trama interwoven, homogeneous. Pileus cuticle differentiated as a trichodermium of interwoven hyphae with numerous free hyphal tips, frequently tapering toward the free end, not appearing cystidioid, pale ochraceous in KOH, hyphae ▒8 Ám wide. Stipe cuticle differentiated as a mass of caulocystidia or free hyphal tips, highly irregular in shape and size, ochraceous in KOH, sometimes appearing incrusted. Clamp connections absent.

Chemical reactions KOH-context yellow to pale orange, cuticle red but quickly darkening; NH4OH-context yellow, cuticle negative or darkening slightly; HCl-context pink; HNO3-context pink, cuticle red; sulfoformalin-context yellow; guaiac-context pale blue, cuticle pale blue; FeSO4-context negative to pale gray, cuticle negative to pale gray.

Habit, habitat, and distribution Solitary to scattered in humus under madrone and manzanita. It has been found, so far, only in the coastal hardwood forests of central California and in similar forests at lower elevations in the vicinity of Mount Shasta, but it probably occurs throughout the range of madrone and manzanita. It can be easily overlooked because of the similarity in the color of the cap and dead madrone leaves and also because it is frequently completely covered with leaves, never breaking through to the surface. Unlike many boletes, the basidiocarps of this species often do not appear until at least a month after the onset of the fall rains.

Material studied Amador County: Thiers 26915. El Dorado County: Sundberg 1551. Marin County: Hitsch 12-1-69; Thiers 10873. Mendocino County: Thiers 24188. Napa County: Thiers 10821. San Mateo County: Setzer 1529; Thiers 18174, 18341, 26922, 26929, 27020. Santa Cruz County: Thiers 18553. Shasta County: Thiers 21608, 21635.

Observations This species was originally described as Boletus puniceus; however, that name had been previously applied to a species from China, thereby necessitating the adoption of a new epithet. Boletus amygdalinus shows obvious affinities with B. erythropus, but is readily distinguished by the much paler colors of its pileus and tubes. Even old basidiocarps fail to show the dark-brown color of the pileus or the dark-red pores usually associated with B. erythropus. Boletus amygdalinus also has larger, more ellipsoid spores, larger cystidia, no laticifers in the pileus trama, and a different type of cuticle on the stipe. The probable mycorrhizal hosts for the two species are also different. Other red-pored boletes occurring in the state are readily distinguished either by the color of the pileus, reticulate stipe, or a combination of these and other characters.

The edibility of this species, so far as known, has not been determined. However, if one abides by the general premise of refraining from eating boletes with red pores, then, obviously, it should be avoided.

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
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