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Rugosomyces onychinus

[ Basidiomycota > Agaricales > Lyophyllaceae > Rugosomyces . . . ]

by Michael Kuo

This attractive but fairly rarely encountered mushroom is found under mountain conifers from Idaho to the Four Corners region, and west to the Pacific Northwest. It is reminiscent of Tricholomopsis rutilans, but grows terrestrially rather than on wood. Defining features include a white spore print, yellow gills, and a pinkish to purplish stem.

Calocybe onychina is a synonym.

Thanks to Regan Dixon for collecting, documenting, and preserving Rugosomyces onychinus for study; the collection is now deposited in The Herbarium of Michael Kuo.


Ecology: Probably saprobic; growing alone, scattered, or gregariously under conifers, especially subalpine fir, Engelmann spruce, and Douglas-fir; summer and fall; central Idaho to the Four Corners, west to the Pacific Northwest. The illustrated and described collections are from Colorado and British Columbia.

Cap: 2–5 cm; broadly convex becoming broadly bell-shaped or nearly flat; dry; more or less bald; deep purple to purplish red or purple-brown; the margin inrolled when young.

Gills: Attached to the stem by means of a notch; close; short-gills frequent; dull yellow.

Stem: 2–5 cm long; up to 1 cm wide; more or less equal; dry; fairly bald; purplish.

Flesh: Yellowish; not changing when sliced; thin.

Odor & Taste: Not distinctive.

Chemical Reactions: KOH negative on cap surface.

Spore Print: White.

Microscopic Features: Spores 3–4.5 x 2–3 µ; ellipsoid; smooth; hyaline in KOH; inamyloid. Basidia 4-sterigmate. Hymenial cystidia not found. Lamellar trama parallel. Pileipellis hymeniform; golden orangish brown in KOH; terminal cells clavate, 6–13 µm wide. Clamp connections present.

REFERENCES: (Fries, 1838) Raithelhuber, 1979. (Saccardo, 1887; Moser, 1983; Bessette, Miller, Bessette & Miller, 1995; Desjardin, Wood & Stevens, 2016; Kalamees, 2018.) Herb. Kuo 08110701, 10271801.

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Rugosomyces onychinus

Rugosomyces onychinus

Rugosomyces onychinus

Rugosomyces onychinus
Spore print

Rugosomyces onychinus

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Kuo, M. (2019, January). Rugosomyces onychinus. Retrieved from the MushroomExpert.Com Web site: