Pileus 6-8 cm latus, subviscidus vel viscidus, glaber vel appresso-fibrillosus, brunneus vel rufobrunneus. Contextus 9-14 mm crassus, flavus tactu caeruleus. Sapor et odor mitis. Tubuli 0.5-1 cm longi, olivaceo-brunnei tactu caerulei; pori I mm lati, concolores tactu caerulei. Stipes 10-12 cm longus, 1-1.5 cm crassus, reticulatus, siccus, flavus; contextus flavus tactu caeruleus. Sporae 9-11 X 3-4 m, subfusoideae vel subellipsoideae. Cystidia 18-35 X 7-10 m, fasciculata. Cuticula viscida, intertexta. Holotypus (no. 23616) a H. D. Thiers lectus prope Agnew Meadows, Madera County, August 18, 1969; in Herbarium San Francisco State University conservatus.

Pileus 6-8 cm broad when mature, convex when young, becoming plano-convex with a flared or uplifted margin when mature; surface subviscid to viscid, glabrous to obscurely appressed fibrillose during all stages of development; color brown to reddish brown ("tawny" to "ochraceous-tawny" to "buckthorn brown"); margin entire, glabrous, eroded when old. Context 9-14 mm thick, yellow, changing to blue when exposed. Taste and odor mild.

Tubes 0.5-1 cm long, adnate to adnexed, olive brown ("olive-brown"), changing to blue when bruised or exposed; pores up to 1 mm broad, angular, concolorous with the tubes, bluing when bruised.

Stipe 10-12 cm long, 1-1.5 cm thick at the apex, subequal to subclavate, solid; surface distinctly reticulate on upper one half to two thirds portion, dry, yellow ("antimony yellow") at the apex, darkening slightly toward the base, reticulum concolorous; no evidence of a partial veil. Context yellow in the apex, becoming vinaceous toward the base, bluing in the apex when exposed.

Spore print color unknown. Spores 9-11 X 3-4 m, pale ochraceous in KOH and Melzer's, subfusoid to subellipsoid in face view, inequilateral in profile, walls thin, smooth.

Basidia 20-25 X 7-9 m, four-spored, clavate, hyaline in KOH. Hymenial cystidia 18-35 X 7-10 m, in large clusters or fascicles, basal portion of cluster black in KOH, apical portion dark brown in KOH, clavate.

Tube trama subgelatinous, hyaline in KOH, divergent, hyphae 5-8 m wide. Pileus trama homogeneous, interwoven. Pileus cuticle a closely interwoven ixotrichodermium, pale ochraceous in KOH; hypodermium tightly interwoven, compact. Stipe cuticle differentiated as a layer of fertile basidia with fascicles of caulocystidia interspersed. Clamp connections absent.

Chemical reactions unknown.

Habit, habitat, and distribution Solitary in soil under lodgepole pine. Known only from the vicinity of the Devil's Post Pile National Monument.

Material studied Madera County: Thiers 23616 type.

Observations This is a very distinct species readily recognized by the combination of an almost glabrous pileus, context and tubes that stain blue, and, most especially, by the noticeably reticulate stipe. No other Suillus species known to the author possesses such a stipe. This species does not really have the aspect of a Suillus because of the long, reticulate stipe, which lacks prominent glands on the surface. Because of the bluish discoloration of the flesh and the absence of a veil, it appears to be most closely related to S. tomentosus; however, the latter has a strongly fibrillose scaly pileus and a more or less smooth stipe. Among the other species in which the context changes to blue, S. subvariegatus and S. ruber are easily distinguished by either the fibrillose scales on the pileus or distinctive colors of the basidiocarps; S. caerulescens and S. ponderosus belong to the section Boletinus and are not suggestive of this species.

Edibility unknown.

The Boletes of California
Copyright © 1975 by Dr. Harry D. Thiers
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