SUILLUS MEGAPORINUS Snell and Dick, Mycologia 48: 302. 1956

Illustrations: See Microfiche No. 44

Pileus 2-5 cm broad at maturity, globose to convex when young, becoming broadly convex to plano-convex to highly irregular with age; surface subviscid to viscid, streaked to fibrillose to appressed fibrillose scaly, scales occasionally becoming free when very old; background color tan ("warm buff" to "ochraceous-buff"), scales near light brown ("cinnamon-buff" to "avellaneous"), sometimes becoming rust colored ("ochraceous tawny") when older; margin incurved, with obscure partial veil fragments when young, glabrous at maturity. Context 0.5-1 cm thick, tan ("warm buff" to "ochraceous-buff" to near "cinnamon-buff"), unchanging when exposed. Taste and odor not distinctive.

Tubes up to I cm long, depressed, becoming arcuate-decurrent to strongly decurrent with age, yellow ("antimony yellow" to "chamois"), sometimes reddish ("tawny" to "russet") tints with age, unchanging when exposed, often appearing similar in arrangement to that of Gastroboletus turbinatus; pores up to 5 mm in length and 3 mm broad, intervenose, almost lamellate, with thick, wrinkled, irregular margins, concolorous with tubes, unchanging when bruised.

Stipe 1-3 cm long, 4-7 mm thick at apex, often appearing short and reduced, sometimes somewhat eccentric, pallid to more or less concolorous with the pileus; surface becoming conspicuously glandular dotted at maturity; no annulus, but obscure fibrillose annular zone sometimes apparent. Context concolorous with that of the pileus, unchanging.

Spore print color unknown. Spores 8.5-10.5 X 4.5-6 Ám, ellipsoid to subfusoid to subcylindric, thin-walled, hyaline in KOH, pale yellow in Melzer's.

Basidia 25-30 X5-8 Ám, hyaline in KOH, cylindric, four-spored. Hymenial cystidia 30-48 X 7-11 Ám, rare on sides of tubes, abundant to crowded on pores, fascicled, no solitary cystidia seen, dark brown in KOH, chocolate brown in Melzer's, cylindric to clavate, thin-walled, heavily incrusted.

Tube trama hyaline, appearing subgelatinous in KOH, parallel to regular to obscurely divergent, hyphae 3-4 Ám wide. Pileus trama loosely interwoven, homogeneous, hyaline to pale brown in KOH. Pileus cuticle differentiated as an ixotrichodermium, hyaline to pale buff to pale brown in KOH, rust red ("ochraceous-tawny") in Melzer's; hypodermium compactly interwoven, dark brown in KOH and Melzer's. Stipe cuticle gelatinous in KOH, interwoven, with large clusters of caulocystidia staining dark brown in KOH, often with strong lavender tints, similar in shape and size to the hymenial cystidia. Clamp connections absent.

Chemical reactions NH4OH-cuticle grayish lavender, context rose color, tubes red; HNO3, HCL, H2SO4-cuticle orange, context deep lilac, tubes red; FeSO4-cuticle blue gray.

Habit, habitat, and distribution Gregarious to scattered in soil under conifers at edge of seepage areas. Basidiocarps often occurring in large numbers.

Material studied Fresno County: Thiers 13423, 13440. Tuolumne County: Thiers 21051, 21084, 21085, 21087, 21095, 21097, 21105, 21107.

Observations At the time the monograph by Smith and Thiers was published, no fresh material of this species had been seen. Since that time, however, collections have been made in the type locality and in other areas in the Sierra. This is a highly distinctive Suillus. The arrangement and disposition of the tubes cause the basidiocarp to appear diseased or gastroid, but a spore deposit is delivered. The pores are larger than in any other Suillus and are so long radially that the hymenophore appears distinctly lamellate. The stipe is very reduced, short, and somewhat eccentric. Like S. americanus it sometimes has reddish streaks or fibrils on the surface, but does not resemble that species otherwise. In Snell and Dick's original description, they noted that an ample annulus was sometimes present. This was not apparent on any of the basidiocarps seen, although a fibrillose annular zone could be detected on some. Suillus megaporinus may be somewhat closely related to S. riparius since both species have rather large pores. However, S. riparius has a well-developed stipe, a much darker-colored pileus, with a rough scaly surface, larger cystidia, and a palisade type of cuticle on the stipe.

Edibility unknown.

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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