SUILLUS CALIFORNICUS (Murrill) Thiers comb. nov.
Rostkovites californicus Murrill, Mycologia 7:44. 1915.

"Pileus thick, convex to plane, solitary, 6-9 cm broad; surface smooth; conspicuously subtomentose, brown, margin concolorous, entire, rather thick; context thick, fleshy, flavous, unchanging; taste mild; tubes adnate, plane or slightly convex in mass, 4-6 mm long, yellow, exuding drops which blacken with age, mouths large, angular; spores oblong-ellipsoid, smooth, yellowish brown, 7-8 X 3.5-5 [m]; stipe subequal or bulbous, smooth, yellow, with black dots, unchanging, solid, yellow within, unchanging, 3-6 cm long, 1.5-2 cm thick.

"Type collected on the ground in pine woods in Grass Valley, California, Nov. 12, 1914, H. S. Yates and F. H. Bolster 251 (Herb. N. Y. Bot. Gard.). Excellent field notes accompany the specimens. The species is strikingly different from other members of the genus in having a conspicuously subtomentose surface resembling that of Ceriomyces communis."

The above is a copy of the type description. No fresh basidiocarps of this species have been found. Through the courtesy of the New York Botanical Garden, the type has been examined. The following notes were included with the type collection.

"Number 251.
"Rostkovites californicus sp. nov."
(The first name given by the collector was Rostkovites subaureus but that species epithet had been struck through and californicus substituted.)
"Locality-Grass Valley, Calif.
"Date-November 12, 1914.
"Habitat-On ground in pine woods.
"Pileus-diameter 6-9 cm, subconvex to plane, subtomentose, shiny when fresh, color brown.
"Context fleshy, light yellow unchanging, taste mild.
"Tubes adnate; yellow; 4-6 mm long; mouths large, angular.
"Spores-7-8 X 3.5-4 [m], brown.
"Stipe-Even or somewhat bulbous. 3-6 cm long by 1.5-2 cm in diameter. Color yellow with black granulations. Context of stipe yellow, unchanging. Base somewhat fibrous.
"Remarks-This species seems not to be affected by insects.
"Collector-F. H. Bolster.
"Sent to Murrill, Dec. 11, 1914.
"Notes by Yates."

A microscopic examination of the type collection (which consists of only one half a basidiocarp) yielded the following data on anatomical features.

Spores 9-12 X 3.5-5 m, pale brown in KOH, some dextrinoid in Melzer's, ellipsoid to subovoid, inequilateral and ventricose in profile, smooth, thin-walled.

Basidia 24-29 X 7-9 m, four-spored, clavate, hyaline in KOH, but hymenium pale ochraceous in KOH. Hymenial cystidia 35-46 X 7-10 m, moderately thick walled, fascicled; dark brown in KOH, dextrinoid in Melzer's; more abundant at pores, some hyaline cystidia in clusters, clavate to somewhat irregular in outline, numerous solitary cystidia breaking free from the clusters and floating in the mount.

Tube trama strongly divergent, subgelatinous, hyaline in KOH, hyphae 4-6 m wide. Pileus trama homogeneous, ochraceous in KOH, bright red in Melzer's. Pileus cuticle differentiated as a layer of narrow, interwoven hyphae that are subgelatinous, no pileocystidia or fascicles of erect hyphal tips seen, hyphae 3-5 m wide, pale ochraceous in KOH, slightly darker in Melzer's. Stipe cuticle differentiated as a layer of fertile basidia with fascicles of caulocystidia interspersed. Clamp connections not seen.

Since no fresh material of the species has been available to this author, it is very difficult to make a satisfactory disposition of this bolete. The microscopic features clearly indicate that it is a Suillus, but because of the peculiar combination of characters its placement in the proper subgeneric categories is beset with problems. The most distinctive features are the almost dry, subtomentose cap (although the notes indicate it was "shiny" when fresh), the yellow context that does not change to blue upon exposure, the large pores and the relatively large spores.

The color of the cap of the type specimen is near cinnamon to ochraceous tawny with slightly darker fibrils, and its appearance is not truly suggestive of any Suillus known from the state. Suillus fuscotomentosus is much darker colored, has small pores and often an unpleasant taste, but like S. californicus the cap surface is strongly fibrillose. Also, S. fuscotomentosus has relatively large spores and apparently forms mycorrhizal associations with ponderosa pine. The two species are probably the most closely related of those in this area. Suillus tomentosus, another species with a fibrillose pileus, is distinctly viscid, more yellow in color, has fibrils that are often gray when young and reddish when old, and the context changes to blue when exposed.

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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