The North American species of Psathyrella.

1972]

PSATHYRELLA

313

and with a thin coating of superficial fibrils from the veil, glabrescent, pruinose
above, not discoloring over lower portion.
Spore deposit black. Spores 8-11 (-12) x 5-6 I,, smooth, with a distinct hyaline
lens-shaped apical pore, shape in face view elliptic to slightly ovate, in profile
subelliptic, color in KOH dark bister but becoming chocolate-black in KOH, in
Melzer's reddish tawny, wall 0.6-0.8 pg thick.
Basidia 20-25 x 8-10 a, 4-spored, clavate, hyaline in KOH. Brachybasidioles
present. Pleurocystidia scattered (34-)40-60 x 9-16 g, fusoid-ventricose and with
narrow neck and acute to subacute apex, hyaline in KOH, smooth, thin-walled,
content not distinctive in KOH or Melzer's. Cheilocystidia similar to pleurocystidia but usually shorter and varying to broadly fusoid; clavate to vesiculose
cells also present and these with yellow walls in KOH at times. Caulocystidia
similar to pleurocystidia but larger or vesiculose to versiform-various shapes
and up to 18 p broad.
Cuticle of pileus of vesiculose cells up to 30 u wide, walls hyaline or nearly
so and smooth, cell content not distinctive. Hyphae of trama vinaceous-brown in
KOH and conspicuously incrusted. Clamps present. No distinctive reaction on
any tissue when mounted in Melzer's.
Type locality. Upper Priest River, Boundary County, Idaho.
Habit and habitat. Gregarious on moss in a swampy area.
Distribution. Northern Idaho.
Observations. This species features a cold wet habitat on mosses, a long
slender stipe which is very fragile to go along with the habitat, practically black
spores in deposit, a fibrillose pileus soon glabrescent, subacute to acute pleurocystidia and medium-sized spores with a broad lens-shaped pore apparatus at the
apex. It is dedicated to Father Roothaan, who directed much of the early exploration of the Priest Lake Country in the fur trading days.
283. Psathyrella cheyennensis A. H. Smith, sp. nov.
Pileus 1-2.5 cm latus, conicus vel convexus, glaber, castaneus; lamellae confertae, latae, vinaceo-brunneae (in exsiccatis); stipes 3-6 cm longus, 1-2.5 mm
crassus, glaber, deorsum sordide brunneus; velum sparsum; sporae 9-11(-12) x
5-6.5 gA, pleurocystidia 46-60 x 10-14 u, fusoide ventricosa, acute vel subcapitata;
fibulae adsunt. Typus. Smith 34769 (MICH); legit prope Laramie, Wyoming.
Illust. Text Figs. 604-607.
Pileus 1-2.5 cm broad, obtuse, expanding to broadly conic or convex, surface
glabrous and moist, dark reddish brown (near chestnut-brown) moist, near wood
brown when faded, veil rudimentary and in buttons leaving a few fibrils scattered
along the margin. Context thin and fragile, brown when moist, paler faded, odor
not distinctive, taste not recorded.
Lamellae close, broad, adnate, near "Natal brown" (dark vinaceous-brown)
when dried, edges pallid.
Stipe 3-6 cm long, 1-2.5 mm thick, equal, fragile, glabrous, or lower part at
first faintly fibrillose from remnants of a thin veil, dingy brownish below in age.
Spores 9-11 (-12) x 5-6.5 gu, smooth, truncate (often obscurely) from an apical
or oblique pore, shape in face view ovate to elliptic, in profile obscurely beanshaped to obscurely inequilateral, color in KOH dull cocoa-color slowly becoming
chocolate-brown and finally dark chocolate, tawny in Melzer's, wall about 0.6 j
thick.
Basidia 4-spored. Pleurocystidia 46-60 x 10-14 /, fusoid-ventricose with nar