Syll. fung. 5: 778. 1887.
Common Name: none
Misapplied name: Inocybe pyriodora sensu auct.
Cap 2.5-6.5 (8.0) cm broad, obtuse-conic to bell-shaped in youth expanding to nearly plane, often with a low umbo; margin at first incurved, fringed with veil fibrils, eventually decurved, occasionally wavy; surface when young and unexposed, white, covered with appressed fibrils which become ochre-brown to brown with age and handling, sometimes spotted reddish-brown; context up to 5 mm thick near the stipe, white, soft, reddening erratically; odor strong, matsutake-like, or of rotting fruit; taste mild.
Gills adnate, notched, to narrowly adnexed, sometimes appearing free, close, at first pale greyish-buff, maturing dull-brown, moderately broad, up to 8 mm in width, minutely fringed, the edges lighter than the faces; lamellulae in three to four series.
Stipe 40-80 mm long, 5-17 mm thick, round, solid, fleshy-fibrous, more or less equal, sometimes with a basal bend and sub-bulbous; surface striate-fibrillose, white, remaining so at the apex, the lower half to two-thirds becoming brown to dingy reddish-brown with age and handling; partial veil cortinate, evanescent, sometimes leaving scattered brown fibrils mid-way on the stipe.
Spores 9.0-11.5 x 5.5-7.0 µm, smooth, moderately thick-walled, amygdaliform in face-view with an apical papilla, strongly inequilateral in profile, shaped like an orange wedge; spores brown in deposit; pleurocystidia and cheilocystidia with encrusted apices present but uncommon; encrusted caulocystidia absent.
Solitary or in small groups under oaks (Quercus spp.) and conifers; fruiting from late fall to mid-winter in coastal forests; likely also present in the Sierra Nevada; occasional.
Unknown; to be avoided; many Inocybe species contain the toxin muscarine.
Inocybe fraudans, known as Inocybe pyriodora in older field guides, could be confused with a number of Inocybes were it not for a strong matsutake-like or aromatic fruity odor. In California only Inocybe corydalina has a similar odor, but it differs in developing greenish discolorations on the cap and stipe base. Principal fieldmarks of Inocybe fraudans are a whitish, fibrillose, usually umbonate cap that becomes ochre-brown to medium-brown with exposure and handling. Additionally, both cap and stipe may develop reddish-brown stains where injured. Microscopically, the occasional presence of encrusted pleurocystidia and cheilocystidia, and absence of encrusted caulocystidia also help define the species.
Kuyper, T.W. (1986). A Revision of the Genus Inocybe in Europe. I. Subgenus Insperma and the Smooth-Spored Species of Subgenus Inocybe. Rijksherbarium: Leiden, Netherlands. 247 p.
Nishida, F.H. (1987). The Genus Inocybe in Southern California (Agaricales, Basidiomycetes). Masters Thesis. California State University, Los Angeles: Los Angeles, CA. 315 p.
Nishida, F.H. (1989). Key to the Species of Inocybe in California. Mycotaxon 34(1): 181-196.