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

The Subgenus Hebeloma

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reaction, rather heavy grayish veil, and dextrinoid debris in the cuticle
of the pileus make a distinctive combination of characters. H. nigellum
resembles it in some respects, but has a raphanoid then bitter taste,
and the pileus lacks a violaceous tone. H. kuehneri is also close but in
H. obscurum the gills are pallid then avellaneous, and the veil is gray.
68. Hebeloma griseovelatum sp. nov.
Pileus 2-2.5 cm latus, demum planus vel obscure umbonatus,
umbrinorufus deinde sordide fulvus, subviscidus, leviter fibrillosus, canescens; contextus tenuis, pallide argillaceus, odor et gustus mitis. Lamellae adnatae, confertae, angustae demum sublatae. Stipes 3-4 cm
longus, 3-5 mm crassus, deorsum fulvus, griseofibrillosus. Velum griseum, fibrillosum. Sporae 9-12 x 4.5-6 RJm, inequilaterales, minute
rugulosae. Basidia tetraspora. Pleurocystidia nulla. Cheilocystidia fusoide ventricosa vel subclavata, 42-70 x 4-10 pJm, et 27 x 9 Vxm.
Specimen typicum in Herb. Univ. Mich. conservatum est, Smith
86929; legit prope Independence Pass, Pitkin County, Colorado, 27 Jul
1976.
Pileus 2-2.5 cm broad, obtuse, the margin inrolled, expanding to
plane or with an obscure umbo, color evenly pale "Warm Sepia," fading
to dull tawny, margin inrolled and long remaining so; slightly viscid,
fibrillose and appearing hoary. Context thin, more or less pliant-firm,
pale buff; odor and taste not distinctive. FeSO4 olive-fuscous in cap and
stipe; with KOH no reaction.
Lamellae narrow becoming only moderately broad, moderately
close, broadly adnate or with a decurrent tooth, grayish (near avellaneous) then more or less "Verona Brown," not beaded and not staining.
Stipe 3-4 cm long, 3-5 mm thick, dark rusty brown in the base
and changing to brown upward gradually, firm, soon hollow, surface
grayish fibrillose, apex + naked, some long-striate in age. Veil fibrils
grayish.
Spores 9-12 x 4.5-6 pJm, inequilateral in profile, elliptic in face
view, minutely rugulose, very pale yellowish in KOH.
Hymenium.-Basidia 4-spored. Pleurocystidia none. Cheilocystidia of two types: a) 42-70 x 4-10 Rxm and fusoid-ventricose, and b)
27 x 9 Jim and ~ clavate.
Lamellar and pilear tissues.-Lamellar trama typical of the genus.
Cuticle of pileus a thin layer of gelatinous hyphae (a rudimentary
ixocutis). Hypodermium cellular. Stipe cuticle dry, hyphae repent.
Caulocystidia as terminal elements on epicuticular hyphae of stipe and
similar to the cheilocystidia.
Habit, habitat, and distribution.-On soil, gregarious, under con