The North American species of Psathyrella.

1972]

PSATHYRELLA

269

with obtuse apex; wall thin, smooth and hyaline; caulocystidia not observed.
Cuticle of pileus a layer of vesiculose cells 2-3 cells deep, walls smooth and
hyaline to yellowish in KOH, subcuticular region of inflated hyphal cells
vinaceous-brown revived in KOH and the hyphae of the gill trama the same,
elongate inclusions (crystals) present in pilear and lamellar tramae when fresh
and as revived (in either KOH or Melzer's). Clamps present. No distinctive
amyloid reactions observed in any tissue or any type of cell.
Type locality. Priest Lake, Idaho.
Habit and habitat. Scattered on cow dung.
Distribution. Known only from the type locality.
Observations. The distinguishing features of the species are the large black
spores, the benzo brown pileus when fresh, delicate silvery stipe, practical absence
of pleurocystidia, and lack of a change to pink in age.
229. Psathyrella equina A. H. Smith, sp. nov.
Pileus 1.5-4 cm latus, conicus, glaber, cinnamomeo-brunneus; contextu dilute
brunneus; lamellae latae, confertae, albidae demum subfuscae; stipes 4-6 cm
longus, 2.5-3.5 mm crassus, albidus, sursum pruinosus; velum parvum; sporae
11-13x5.5-7 L; pleurocystidia nulla; fibulae adsunt. Typus. Smith 15816
(MICH); legit prope McCall, Idaho.
Illust. Text Figs. 526, 527.
Pileus 1.5-4 cm broad, obtusely conic, expanding to broadly conic but not
becoming convex, surface glabrous or the margin with a faint fringe of white
fibrils at first, moist but not translucent-striate "cinnamon-brown" to "Prout's
brown" or nearly "mummy brown" in age, hygrophanous, fading to "cinnamonbuff" or nearly whitish. Context very thin and equal, very fragile, watery brown
but soon fading to buff or whitish, odor and taste not distinctive.
Lamellae ascending adnate and soon seceding, moderately broad and oval in
outline, close, 20-24 reach the stipe, 1-2 tiers of lamellulae, white when young,
dull grayish brown in age.
Stipe 4-6 cm long, 2.5-3.5 mm thick at apex, slightly enlarged below, hollow,
white, unpolished, pruinose above, veil remnants very slight and not leaving a
fibrillose zone.
Spores 11-13 x 5.5-7 I, smooth apical pore small and apex obscurely truncate,
shape in face view elliptic to slightly ovate, in profile elliptic to subelliptic, color
in KOH near "mummy brown" becoming dark chocolate-color slowly, in Melzer's
tawny if immature, bay-colored in old ones, wall about 1 J, thick.
Basidia 18-23 x 10-13 /t, broadly clavate, hyaline in KOH. Brachybasidioles
present. Pleurocystidia absent. Cheilocystidia 22-36x7-12 ta, somewhat ventricose with generally broadly rounded apex, thin-walled, smooth, hyaline, content
not distinctive in either KOH or in Melzer's. Caulocystidia scattered in groups,
subcylindric to narrowly ventricose and apex rounded to obtuse, some filamentousflexuous end cells also present.
Gill trama of more or less parallel hyphae of broad short cells, hyaline to pale
chocolate-color in KOH, darker toward the base of the gill. Pileus trama dark
cocoa-brown to sordid rusty brown near the gills, paler and only dull brownish
in the subcuticular region. Pileus cuticle of vesiculose cells but not very sharply
differentiated from the cells of the upper half of the trama, hyaline to dull brownish in KOH. Clamps present but inconspicuous. No distinctive reactions noted
on any tissue as mounted in Melzer's.