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Species Information
Summary: Subgenus Dermocybe. 1) A characteristic feature is the tendency of the cap to lose moisture and fade from dark reddish brown (often with some olive tones) to olive-brown (subhygrophanous). 2) The most striking characteristic when present is microscopic: the presence of bluish to bluish purple particles of pigment in the hyphae of the cuticle and subcuticle of cap when mounted in KOH. Other features include 3) broad gills that are ochraceous when young, 4) a dry, equal stem that is yellowish to ochraceous when young with a covering of ocher brown fibrils, darkening to more ocher brown as it ages, 5) a sometimes bitter taste, and 6) a reddish brown cap reaction with KOH.
Cortinarius idahoensis has been found at least in ID and WA, (Ammirati), and BC (collections by O. Ceska at University of British Columbia). The accompanying photo by Noah Siegel was taken in CA.
Cap: (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
Flesh: in cap olive when moist, ochraceous faded, in stem rusty ochraceous to the base, in base orange-fulvous to dark fulvous
Gills: "adnexed, close, broad"; rusty ochraceous becoming ferruginous, then orange-ochraceous to orange-fulvous, (Ammirati), broadly attached "or with a slight notch and a decurrent tooth", "closely spaced"; yellowish brown to ocher-brown when young, "becoming more ocher-orange as spores mature", (Siegel)
Stem: 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", (Ammirati), 3-8cm x 0.5-1.0cm, "more or less equal, or with a slightly enlarged base", "stuffed with pith when young, soon becoming hollow"; "Yellowish to yellowish buff with darker, ocher-brown fibrils, darkening more toward ocher-brown as it ages, basal mycelium pale creamy yellowish, staining dingy yellowish when handled"; "dry, covered with silky longitudinal fibrils", (Siegel)
Veil: sparse cortina "of pale ocher-brown fibrils, leaving silky fibrils on the stipe, or disappearing altogether", (Siegel)
Odor: not distinctive (Ammirati), indistinct (Siegel)
Taste: more or less bitter (Ammirati), indistinct (Siegel)
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, (Ammirati), spores 7-9 x 4.5-5.5 microns, elliptic, minutely roughened; cells of cap surface with bluish particles in KOH, (Siegel)
Spore deposit: rusty brown (Siegel)
Habitat / Range
gregarious "under conifers on humus or rotted wood, September through November", (Ammirati), single or scattered "on ground or on well-rotted wood under pine, but reported with other conifers as well"; "late fall or winter", (Siegel)
Similar Species
Cortinarius zakii is similar in having orange gills, but 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). Cortinarius aurantiobasis has orange gills, but has large spores (8.5-11(12) x 5-6 microns), (Ammirati). Cortinarius ominosus and its relatives and Cortinarius humboldtensis are similar in the presence of blue to bluish purple particles of pigment in hyphae of cuticle and subcuticle of cap, however C. ominosus has red gills and C. humboldtensis has olive-yellow gills, (Ammirati). C. humboldtensis "has an olive-yellow to cinnamon-brown cap, olive-yellow to ocher-yellow gills, and a dark inky violet KOH reaction on the cap", (Siegel). Cortinarius croceus "has a warm cinnamon brown cap, yellowish gills with a greenish hue when young, and dingy olive-yellow flesh", (Siegel). Members of the Cortinarius cinnamomeus group "have bright orange gills from the start", (Siegel). See also SIMILAR section of Cortinarius ceskae.
