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

Lamellar and pilear tissues.-Cuticle of pileus a thin ixocutis or a
"subixocutis" (only a few hyphae deep and these scarcely gelatinous),
hyphae 2-3 (4) xjm diam, tubular, clamps present. Hypodermium of
inflated but elongated hyphal cells, rusty brown as revived in KOH
and distinctly encrusted (the layer intermediate between hyphoid and
cellular). Tramal hyphae of pileus and lamellae typical of the genus but
red as revived in Melzer's, soon fading.
Habit, habitat, and distribution.-Gregarious to caespitose on a
lawn under Pinus strobus, following several weeks of killing frost at
night, Bar Harbor, Mt. Desert Isl., Hancock County, Maine, October
29, 1980 (type, MICH).
Observations.-A thin fibrillose veil is still visible on the stipe in
young fruiting bodies, but the pileus margin lacks the patches of
fibrils characteristic of H. mesophaeum. H. littenii appears to be closest to H. subrimosum but is not Inocybe-like in the appearance of the
fruiting bodies, and the western species does not have a translucent
cap when moist. The dark-colored spore deposit of H. littenii is in
contrast to its nearly hyaline spores as mounted in KOH and viewed
under the microscope.
101. Hebeloma mesophaeum var. longipes var. nov. (h)
Pileus 2-6 cm latus, campanulatus vel plano-umbonatus, viscidus,
argillaceus, ad marginem fibrillose appendiculatus, glabrescens. Contextus pallide argillaceus; odor et gustus raphanoideus. Lamellae pallidae dein avellaneae demum sordide cinnamomeae. Stipes 5-11 cm
longus, 5-10 mm crassus, sursum pallidus, deorsum brunnescens,
sparse fibrillosus. Velum pallidum, sparsum, fibrillosum, evanescens.
Sporae 8-10 x 5-6 Lim, ovoideae vel ellipsoideae, non dextrinoideae,
subleves, in "KOH" pallide argillaceae. Cheilocystidia 32-41 ( 60+)
prm longa, 6-9 tLm lata ad basim, sursum 4-6 VIm lata.
Specimen typicum in Herb. Univ. Mich. conservatum est, Smith
64681; legit sub Pini, prope Dexter, Michigan, 14 Oct 1961.
Pileus 2-6 cm broad, obtuse to campanulate, expanding to
broadly campanulate, sometimes plane or with a low umbo, surface
viscid, margin fringed with fibrils but soon glabrescent, disc clay color
to cinnamon-buff, margin pinkish buff or paler, (as dried in the herbarium) the disc alutaceous and the margin dull pinkish buff. Context
thin, pale dingy buff when faded, odor and taste raphanoid, KOH and
FeSO4 neither one staining the cuticle or context.
Lamellae whitish becoming avellaneous and finally pale "Sayal
Brown," close, broad, adnate to adnexed, edges slightly uneven, not
beaded or spotted.