Mycotaxon 116: 321. 2011.
Common Name: none
Cap 40-100 cm broad, convex, becoming plano-convex, at maturity sometimes centrally depressed; margin incurved, in age occasionally wavy and upturned; surface viscid, often with adhering debris; color cream to yellowish, disc brown to reddish brown from innate fibrils; surface bruising buff to ochre-tan, KOH reaction on surface pale reddish brown; context firm, up to 10 mm thick, cream-colored to tan when exposed, KOH reaction brownish; odor and taste mild.
Gills close, shallowly notched, sometimes with a short decurrent tooth, cream yellow in youth, dull brown in age, edges even, concolorous with faces; lamellulae in 3-4 series.
Spores 9-12 x 5-6.5 µm, almond-shaped in faceview, inequilateral in profile, warted at 1000X, hilar appendage prominent; spores rusty brown in deposit.
Solitary or in small groups in duff of oaks (Quercus spp.) and tanbark oak (Notholithocarpus densiflorus); found in coastal forests and foothills of the Sierra Nevada; fruiting from after fall rains to midwinter; occasional to common.
Cortinarius xanthodryophilus is a robust, oak-loving species recognized by a glutinous to viscid cap that is cream to yellowish in color, often with reddish brown to brown tints at the disc, and a cylindrical stipe with an abruptly bulbous, marginate base. These features while helpful are not definitive and are seen in several California Cortinarius species in the subgenus Phlegmacium. Of these, Cortinarius fulmineus is most similar. Also an oak dweller, according to Bojantchev & Davis, it differs in having a cap and context that bruise reddish brown, a KOH reaction that turns the cap surface purplish red and the cap context pinkish red. It also has slightly smaller spores- about one micron shorter than those of C. xanthodryophilus. Another mimic, Cortinarius elegantior, also has a viscid, yellowish cap and abruptly bulbous stipe base, but is associated mostly with conifers. When found with C. xanthodryophilus in mixed woods, it can be distinguished by a pronounced red KOH reaction on the cap and basal bulb of the stipe
Bojantchev, D. & Davis, R.M. (2011). Cortinarius xanthodryophilus sp. nov. a common Phlegmacium under oaks in California. Mycotaxon 116(1): 317-328. (Protologue)
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.