Pluteus mammillatus (Chamaeota sphaerospora)

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by Michael Kuo

This fascinating and rare mushroom was known as Chamaeota sphaerospora until recently, when Pluteus expert Drew Minnis and his collaborators (2006) placed it in the genus Pluteus, with the support of morphological and DNA evidence, as the only species with a ring (the authors also synonymized Chamaeota mammillata, which had the older name and thus received the species epithet).

Although Pluteus mammillatus is extremely rare everywhere else, it is quite common in the Mingo National Wildlife Refuge, site of a fantastic annual foray for the Missouri Mycological Society.

Description:

Ecology: Saprobic on the decaying wood of hardwoods; growing alone or gregariously; summer and fall; distribution uncertain (originally recorded from Michigan, but rarely reported since, except in southeastern Missouri).

Cap: 1-7 cm; conical at first, becoming broadly bell-shaped, broadly convex, or nearly flat; dry; finely silky; medium to bright yellow, fading on exposure; the margin slightly lined.

Gills: Free from the stem; close; whitish at first, becoming pink at maturity.

Stem: 1-8 cm long; up to 1.5 cm thick; equal or tapering upward; solid; smooth or finely silky; whitish to pale yellowish; with a fragile white ring on the lower half.

Flesh: Insubstantial; white.

Odor and Taste: Not distinctive.

Spore Print: Pink.

Chemical Reactions: KOH negative on cap surface.

Microscopic Features: Spores 5-7 µ; round or nearly so; smooth. Cystidia abundant; variously shaped but usually fusoid-ventricose or broadly clavate; up to 100 µ long and 30 µ wide.

REFERENCES: (Longyear, 1902) Minnis, Sundberg & Methven, 2006. (Saccardo, 1912; Kauffman, 1918; Singer, 1978; Miller & Miller, 2006; Minnis, Sundberg, Methven et al., 2006.) Herb. Kuo 09180401.

Pluteus mamillatus (with one m) is an alternate spelling.

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Cite this page as:

Kuo, M. (2009, June). Pluteus mammillatus (Chamaeota sphaerospora). Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/pluteus_mammillatus.html