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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in the form of an ixotrichodermium, in the slightly larger paler
spores (in both KOH and Melzer's), and in lacking a raphanoid
odor and taste.
6. Hebeloma subboreale sp. nov.
Pileus 1.5-3 cm latus, obtusus vel convexus, demum planus, rufobrunneus ad centrum, ad marginem incarnato-argillaceus, glaber, viscidus, subhygrophanus odor et gustus mitis. Lamellae latae, subdistantes, ventricosae, brunneolae demum cinnamomeae. Stipes 2-4 cm
longus, 1.5-2.5 mm crassus, demum triste brunneus. Velum sordide
ochraceum. Sporae 10-13 x 6.5-7.5 pmr, dextrinoideae, leves in
"KOH," ovoideae, apice subacutae. Basidia tetraspora. Cheilocystidia
43-70 x 8-12 ptm, elongate fusoid-ventricosa, mox subhyalina.
Specimen typicum in Univ. Mich. Herb. conservatum est, Smith
89006; legit prope Elk Camp, Burnt Mt., Pitkin County, Colorado, 16
Aug 1978.
Pileus 1.5-3 cm broad, obtuse to convex, becoming plane, glabrous, viscid, dark "Verona Brown" over the disc, paler and dull
pinkish tan over the margin, opaque at all times, subhygrophanous,
when faded tawny around the disc. Context thin, watery, dark brown
fading to dingy pinkish buff, FeSO4 staining base of stipe inky black;
odor and taste not distinctive.
Lamellae broad, + subdistant, adnate, becoming ventricose,
brownish then pale dull cinnamon ("Sayal Brown"), not beaded and
not staining.
Stipe 2-4 cm long, 1.5-2.5 mm thick, equal, at first pale brown
and silky, dark brown overall in age. Veil of pale buff fibrils, the
remnants forming a thin layer but this soon obliterated.
Spore deposit about "Sayal Brown" either moist or air-dried.
Spores (9) 10-13 x 6.5-7.5 pJm, pale snuff brown in KOH, slowly
dextrinoid, in profile ovate to obscurely inequilateral, in face view
broadly ovate, smooth in KOH, faintly marbled as mounted in
Melzer's.
Hymenium.-Basidia 4-spored, 24-30 x 7-9 iim. Pleurocystidia
none. Cheilocystidia 43-70 x 8-12,um, fusoid-ventricose and finally
greatly elongated, refractive in KOH in some (but the side walls
clearly defined and rigid as well as at times faintly brownish and very
slightly thickened), some filamentous cells also present, these up to
100 x 5-6 x 6-8 Vm, also some cheilocystidia with a secondary septum near the base.