Cortinarius idahoensis Ammirati & A.H. Sm.
no common name

Species account author: Ian Gibson.
Extracted from Matchmaker: Mushrooms of the Pacific Northwest.

Introduction to the Macrofungi


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E-Flora BC Static Map

Distribution of Cortinarius idahoensis
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Species Information

(1)2-4cm across, obtuse to convex, becoming broadly convex to flat, margin incurved to decurved [downcurved]; subhygrophanous [somewhat hygrophanous], dark brown to dark cinnamon, often fading as it dries to olive brown; fibrillose, moist, more or less opaque
in cap olive when moist, ochraceous faded, in stem rusty ochraceous to the base, in base orange-fulvous to dark fulvous
adnexed, close, broad; rusty ochraceous becoming ferruginous, then orange-ochraceous to orange-fulvous
4-7cm x 0.5-1cm, equal or nearly equal, "near rusty ochraceous and darkening (more ochraceous) from the base upward, with a covering of ochraceous fibrils"
not distinctive
more or less bitter
Microscopic spores:
spores 7-9 x 4.5-5.5 microns, elliptic to ovate, verruculose [finely warty], in KOH brownish to pale fulvous, in Melzer's reagent light yellowish to yellowish brown; basidia 4-spored, 24-35 x 5.5-7 microns, "clavate to more or less ventricose, thin-walled", in KOH colorless to pale vinaceous "or containing particles and masses of deep red to vinaceous red pigment", in Melzer's reagent light yellow "or containing yellowish, brownish, orange, or reddish orange particles"; pleurocystidia absent, cheilocystidia 8-17 x 6-8 microns, "clavate to broadly clavate, thin-walled", in KOH and Melzer's reagent similar to basidia; clamp connections present throughout the fruiting body
Spore deposit:
[presumably a shade of brown]

Habitat and Range

like Cortinarius zakii in having orange gills, but C. zakii has deep orange gills when young, spores (6)6.5-8(9) x 4-4.5 microns, and a coating of dull brown to vinaceous brown fibrils over the stem surface, (Ammirati); like Cortinarius aurantiobasis in having orange gills, but C. aurantiobasis has large spores (8.5-11(12) x 5-6 microns), (Ammirati); like Cortinarius ominosus and its relatives and like Cortinarius humboldtensis in the presence of blue to bluish purple particles of pigment in hyphae of cuticle and subcuticle of cap, however Cortinarius ominosus has red gills and Cortinarius humboldtensis has olive-yellow gills, (Ammirati)
gregarious "under conifers on humus or rotted wood, September through November", (Ammirati), fall