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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tis. Lamellae latae, confertae demum subdistantes, ventricosae, adnatae, obscure cinnamomeae. Stipes + 3 cm longus, 2-4 mm crassus,
deorsum brunnescens, sursum pallidus fibrillosus; annulus albofibrillosus. Sporae 8.5-10 x 5-5.5 Rim, subleves, in "KOH" pallide ochraceae, ovoideae vel ellipsoideae. Basidia tetraspora et bispora. Cheilocystidia 38-45 x 5-6 [Im, cylindrica vel anguste clavata.
Specimen typicum in Herb. Univ. Mich. conservatum est, Smith
89095; legit in graminis, prope Independence Pass, Pitkin County,
Colorado, 21 Aug 1978.
Pileus 1-2.5 cm broad, plane with a slight umbo, surface dry to
the touch, thinly white fibrillose overall, ground color alutaceous, in
age with appressed patches of veil fibrils along the margin. Context
thin, grayish pallid fading to whitish; odor strongly pungent, taste
slight; FeSO4 on stipe base olive-fuscous.
Lamellae broad becoming ventricose, close, adnate, finally subdistant, dull cinnamon at maturity; edges not beaded or stained.
Stipe about 3 cm long and 2-4 mm thick, equal, pallid above,
becoming brown below, with a whitish fibrillose superior annulus, fibrillose below the annulus. Veil white and copious.
Spores 8.5-10 x 5-5.5 pJm, ovoid to ellipsoid, in KOH under
high-dry lens + smooth, not dextrinoid, pale ochraceous in KOH.
Hymenium.-Basidia 4- and 2-spored, 28-30 x 5-7 pm. Pleurocystidia none. Cheilocystidia 38-45 x 5-6 Rxm, narrowly clavate to
cylindric, obtuse, basal area scarcely enlarged.
Lamellar and pilear tissues.-Lamellar trama typical of the genus.
Cuticle of pileus an ixotrichodermium, the elements slender (2-3 JLm
diam), clamped, hyaline. Hypodermium cellular, the cells 10-20 iim
diam, with walls heavily encrusted with yellow-brown material. Trama
of pileus typical for the genus.
Habit, habitat, and distribution.-Solitary in grass, spruce nearby,
Independence Pass area, Pitkin County, Colorado, August 21, 1978,
Smith 89095 (type, MICH). It was also collected by Kauffman at Tolland, Colorado, August 26, 1920.
Observations.-This species might possibly be H. testaceum of
Europe but we did not find cheilocystidia with secondary septa as
shown by Bruchet, and neither the odor nor taste "fit" his description
well. Moser (1978) gives the spores of H. testaceum as (8) 10-12 (13)
x 5-6.5 fJm and lists the habitat as moist places under hardwoods.
14. Hebeloma riparium sp. nov.
Pileus 1-3.6 cm latus, obtusus demum convexus vel umbonatus,
spadiceus, demum obscure cinnamomeus, canescens, odor et gustus
mitis. Lamellae "Vinaceous-Buff" demum sordide cinnamomeae, con