The veiled species of Hebeloma in the western United States / Alexander H. Smith, Vera Stucky Evenson, and Duane H. Mitchel.

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The Veiled Species of Hebeloma

Specimen typicum in Herb. Univ. Mich. conservatum est, Smith
90628; legit prope Elk Camp, Burnt Mt., Pitkin County, Colorado, 29
Aug 1980.
Pileus 1-2.5 cm broad, convex becoming broadly convex, at first
with inconspicuous patches of pale buff fibrils along the margin, soon
glabrous, subviscid and soon dry, evenly colored + "Cinnamon
Brown" but fading on margin first to "Verona Brown" or paler, disc
remaining cinnamon-brown. Context white or along the gill-line
brownish, odor pungent, taste very bitter; FeSO4 staining base of stipe
black.
Lamellae close, broad, adnate, pinkish buff becoming dull cocoa
color ("Sayal Brown").
Stipe 2-4 cm long, 2.5-4 mm thick, equal, brunnescent from the
base upward but at first pallid overall, in age apex typically paler than
lower part; fibrillose at first from the buff-colored veil but often glabrous in age (rarely with a thin annular zone of veil fibrils).
Spores (11) 12-14 x 6.5-8 pJm, inequilateral in profile, ovate in
face view, smooth in KOH, in Melzer's faintly punctate and weakly
dextrinoid, pale tawny as revived in KOH.
Hymenium.-Basidia narrowly clavate, 4-spored, 8-10 Jim
broad, often containing fine globules near apex when first revived in
KOH, lower portion + orange-ochraceous in Melzer's. Pleurocystidia
none. Cheilocystidia abundant, scattered to bunched, 38-67 x 6-12 x
4-6 pIm, fusoid ventricose, apex obtuse; and filamentous and 26-64 x
4-6 [Lm, not enlarged at apex, hyaline or as revived in KOH, the walls
faintly brownish after 15 minutes.
Lamellar and pilear tissues.-Gill trama typical of the genus except for the orange-yellow tone in Melzer's; the cells elongate and
walls thin and smooth, dextrinoid debris present but hardly significant.
Cuticle of pileus a very thin cutis to an ixocutis, the layer 2-3 hyphae
deep, hyaline or nearly so; clamps present. Hypodermium intermediate (elements of both types present), walls heavily encrusted with dark
fulvous pigment particles. Trama of pileus yellow-orange in Melzer's
(possibly a red flush at first), dextrinoid debris sparse.
Habit, habitat, and distribution.-Under spruce Elk Camp, Pitkin
County, Colorado, August 29, 1980, Evenson and Smith (type, MICH).
Observations.-This species is clearly distinct by virtue of the
colored veil and very bitter taste. As dried the basidiocarps resemble
those of small specimens of H. mesophaeum but the features of the
spores prevent assignment to that group. It is close to H. marginatulum
var. fallax, especially in view of the slightly colored cheilocystidia in
KOH, but that variety has a raphanoid odor and taste and narrower
cheilocystidia.