Cortinarius pingue

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by Michael Kuo

Formerly known as Thaxterogaster pingue, this Rocky Mountain oddball is actually a "gasteroid" species of Cortinarius. Its cap begins to develop but never opens up to expose the gills, which are consequently poorly formed. The microscopic spore-producing machinery works perfectly well, however, manufacturing Cortinarius-like spores that are presumably dispersed when the cap begins to disintegrate, or when foraging creatures have a yummy meal and continue foraging elsewhere.

Mycologists have long debated the evolutionary significance of gasteroid gilled mushrooms and boletes like Cortinarius pingue, and have often been tempted to see these mushrooms as "transitional" forms. But recent DNA analyses have begun to place gasteroid genera like Thaxterogaster and Rhizopogon (now simply Suillus) smack in the middle of "normal" genera--indicating the likelihood that gasteroid forms evolved independently as adaptations to certain environments.

Cortinarius pingue is a common late summer and fall find under conifers in the Rocky Mountains, and it has been reported from the Cascades and the Sierra Nevada. It has an olive brown, sticky cap, and a whitish cortina. It usually features a fairly well developed stem, but when it grows underground or partially submerged the stem may be rudimentary or nearly absent. The interior of the cap, when sliced open, features a mass of poorly formed, reddish brown gills.

Description:

Ecology: Presumably mycorrhizal with conifers, especially Engelmann Spruce; growing scattered or gregariously, often partially submerged in needle duff; summer and fall; common in the Rocky Mountains but occasionally reported from the Sierra Nevada and the Cascades (under fir).

Cap: 1-5 cm; convex or irregularly blockish; never opening to expose the interior; sticky or slimy; broadly wrinkled or more or less smooth; olive brown or brownish yellow.

Interior: Reddish brown; a mass of poorly formed "gills" and occasional air pockets.

Stem: Sometimes absent or rudimentary (especially in drier regions, where Cortinarius pingue grows partially submerged or nearly underground); 1-4 cm long; up to 2 cm thick; more or less equal; dry; whitish or pale brownish, but often with pinkish or lilac tones; when young with whitish cortina-like fibers that stretch to the edge of the cap.

Flesh: Whitish.

Odor: Strong, reminiscent of the Foetid Russulas.

Microscopic Features: Spores 14-17 x 8-10 µ; more or less elliptical; roughened.

Thaxterogaster pingue is a synonym.

REFERENCES: (Zeller, 1941) Peintner, Moser & Vilgalys, 2002. (Smith, Smith & Weber, 1981; Arora, 1986; Phillips, 1991/2005; Evenson, 1997; Peintner, Moser & Vilgalys, 2002; Peintner, Moncalvo & Vilgalys, 2004.) Herb. Kuo 09010604.

Further Online Information:

Thaxterogaster pingue at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2006, September). Cortinarius pingue. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/cortinarius_pingue.html