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

Lamellae broad (ventricose), close, adnate, ~ "Verona Brown,"
to dull cinnamon at maturity (+ "Sayal Brown"), neither spotted nor
beaded.
Stipe 2-3 cm long, 1.5-2.5 mm thick, equal, fragile, becoming
dark brown at base and then upward; surface silky-fibrillose and grayish, + scurfy from pruina and veil remnants combined; staining brown
when handled.
Spores 11-14 x 6.5-7.5 Rim, + inequilateral in profile, ovate in
face view, clay color revived in KOH, dextrinoid, punctate as viewed
in Melzer's reagent.
Hymenium.-Basidia 4-spored, 7-10 Iim broad near apex; hymenium red in Melzer's. Pleurocystidia none. Cheilocystidia mostly 38-65
x 5-11 x 4-6 iLm, narrowly fusoid-ventricose, apex obtuse to slightly
enlarged; some filamentous and 36-70 x 4-6 pxm, as revived in KOH
ochraceous to + cinnamon-buff in KOH but hyaline after standing for
about 20 minutes.
Lamellar and pilear tissues.-Lamellar trama typical for the genus except for the red color in mounts in Melzer's reagent-but this
soon fading to orange. Cuticle of pileus an ixocutis, the hyphae 2-4
mm diam, clamped, sparingly branched. Hypodermium distinctly hyphoid and in KOH the hyphal walls heavily encrusted with dark
brown material, in Melzer's the incrustations not conspicuous. Tramal hyphae + typical of the genus but red in Melzer's at first but
quickly fading.
Habit, habitat, and distribution.-Scattered under spruce, near
Burnt Mt., Pitkin County, Colorado, August 2, 1980 (type, MICH).
Observations.-The very slender fragile stipe readily staining
brown when handled, lack of both an odor and distinctive taste, and
the conspicuous incrustations on the hypodermal hyphae, are distinctive as a combination. The species appears similar to H. corrugatum,
but in face view the spores are hardly boat-shaped, the veil is grayish
(not clay color), the hypodermium is clearly hyphoid (not at all "cellular"), and the stipe of H. corrugatum is not known to stain brown from
handling.
64. Hebeloma subumbrinum sp. nov.
Pileus 1-2.5 cm latus, convexus vel late expansus, viscidus, canescens "Wood Brown" vel "Avellaneous," ad marginem fibrillosus; odor
raphanicus. Lamellae "Avellaneous" demum incarnato-cinnamomeae,
latae, confertae, adnatae. Stipes 3-5 cm longus, 3-4 mm crassus, obscure brunneus, sursum pallidus; mycelium subroseum. Sporae 10-12.5
x 6-7.5 pm, dextrinoideae. Cheilocystidia 38-76 x 9-12 (21) x 6-7
pjm, fusoid-ventricosa.