The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Type locality. McCall, Idaho.
Habit and habitat. Gregarious on horse dung.
Distribution. Idaho, Michigan.
Observations. The species is close to P. hirta which has a well-developed veil.
Drosophila stercoraria Kiihn. & Josserand is close but the pilei are only 5-8 mm
wide. The American species is not likely to be confused with P. prona.
Material examined. Idaho: Smith 15816 (Type). Michigan: Smith 39414.
230. Psathyrella hirta Peck, Rep. N. Y. State Mus. 50: 107. 1897.
Psathyra semivestita Berk. & Br. var. coprobia Lange, Dansk Bot. Arkiv 9(1): 7.
1936.
Psathyra coprobia (Lange) Lange, Dansk Bot. Arkiv 9(6): 1938.
Psathyrella coprobia (Lange) A. H. Smith, Contr. Univ. Mich. 5: 44. 1941.
Illust. P1. 56 b; P1. 57a.
Pileus 1-2.5(-3) cm broad, obtuse to convex, becoming broadly convex, the
margin at first appressed against the stipe, surface covered by a dense coating of
white patches of fibrils or fibrillose scales, margin fringed with fibrils at first,
glabrescent and soon entirely naked, color "Prout's brown" to "cinnamon-brown"
(dark rusty brown), the margin faintly striatulate when moist, hygrophanous,
fading to near "clay color" or dingy buff in age. Context very fragile, watery
cinnamon-brown, thin, odor and taste mild.
Lamellae squarely adnate or slightly toothed, subdistant, 17-20 reach the
stipe, 2 tiers of lamellulae, broad (up to 1 cm at the stipe), pallid when young,
"fuscous" at maturity, the edges whitish.
Stipe 3-5.5 cm long, 1.5-3.5 mm thick, white, equal, hollow, fragile, densely
white-fibrillose scaly up to the zone left by the broken veil, finally glabrescent,
apex pruinose.
Spores 10-13x 6-7.5(-9) /, smooth, apical hyaline pore distinct but apex not
distinctly truncate, shape in face view elliptic to obscurely ovate, in profile view
elliptic to subelliptic, color in KOH soon dark chocolate-color, in Melzer's dark
bay-brown, wall about 0.5 p thick.
Basidia 4-spored (a few 2-spored), hyaline in KOH, clavate, 16-22x 7-11.
Pleurocystidia abundant, 36-54x6-14 A, fusoid-ventricose but often elongated
and subcylindric; apex acute to subacute; wall thin, smooth and hyaline; content
not distinctive in either KOH or Melzer's. Cheilocystidia similar to pleurocystidia
but usually shorter, some saccate cells present in addition. Caulocystidia scattered
in bunches 34-56x9-14 u, fusoid-ventricose with subacute apex to subfusoid,
hyaline, smooth, thin-walled. Pileocystidia rare and mostly near the pileus margin,
resembling the caulocystidia.
Gill trama regular, the hyphae of enlarged cells and somewhat interwoven,
dingy vinaceous-brown in KOH, the walls with heavier pigmentation near the
septa but no significant degree of incrustation observed. Pileus cuticle of vesiculose hyaline cells the layer about 1 or 1-2 cells deep, the walls smooth and the
cell content not distinctive. Hyphae of the subcuticular region vinaceous-brown
in KOH (in revived sections), no significant degree of incrustation seen. Clamps
present.
Type locality. Minerva, New York.
Habit and habitat. Subcespitose to scattered on manure or fertilized soil.
Distribution. Michigan, New York, Oregon and Washington.
Observations. For the species Smith (1934) previously identified as this species
see P. abortiva of this work. Orton (personal communication) has questioned