The North American species of Psathyrella.

1972]

PSATHYRELLA

155

whitish finally, in old pilei often avellaneous (grayish brown); margin dentateappendiculate from remains of a white veil which is submembranous, the denticulations soon disappearing; surface glabrous over all or the marginal area slightly
appressed-fibrillose at first. Context thin, watery buff then pallid, odor and taste
not distinctive.
Lamellae broad, ascending-adnate, soon seceding, close, pallid, brownish before
the veil breaks, becoming nearly russet but in age with a fuscous cast, not mottled,
edges even.
Stipe 3-6 cm long, 3-5 mm thick, equal, hollow, fragile, white at first and
thinly coated with white fibrils, glabrescent in age dingy watery tan (near
cinnamon-buff) over all, no color change on bruising and not darkening distinctly
from the base upward.
Spores 7-9 (-10) x 4.5-6 /i, smooth, apex rounded but apical pore distinct, shape
in face view ovate to elliptic, in profile subelliptic to elliptic, color as revived in
KOH dark chocolate-color, in Melzer's bright reddish brown, wall about 0.3 t
thick.
Basidia 4-spored, 24-30x8-10 1u, clavate, hyaline in KOH. Pleurocystidia
abundant, 42-62 x 10-16(-20) t/, ventricose-subcapitate to nine-pin-shaped, apex
often flattened, some with 2-3 subapical or apical protuberances (bubble-like in
some), wall smooth and thin, hyaline in KOH, cell content not distinctive in
KOH, in Melzer's often with a yellow inclusion. Cheilocystidia 32-50x9-15 /u,
clavate to ventricose-capitate to fusoid-ventricose or nine-pin-shaped, some with
2-3 subapical extensions, often quite versiform, wall thin and content not
distinctive. Caulocystidia not found.
Pileus with a cuticle of a layer of inflated cells, some pedicellate, the layer
2-4 cells deep, walls thin and nearly hyaline. Hyphae of the subcutis tubular to
inflated, with brownish incrustations as viewed in KOH. Context hyphae below
the subcutis not distinctively colored. Clamps present. No distinctive reactions
noted for any tissue as mounted in Melzer's.
Type locality. New York (Adirondack Mountains).
Habit and habitat. Gregarious on wet mossy sticks in areas where water
accumulates during wet seasons in forests of aspen and birch, May-June.
Distribution. Michigan, New York.
Observations. The Michigan collections described here have the wide spores
and nine-pin-shaped pleurocystidia of the type. The species is apparently not
uncommon, but is missed because of its early fruiting period. Smith (1941)
erroneously identified a different species as Peck's. The correct concept of
P. madeodisca features a dull to bright cinnamon pileus, gills distinctly russet
near maturity, and the pleurocystidia as described. In the Michigan collections
when sections are revived in Melzer's the pleurocystidia show a distinct yellow
inclusion. No record of an inclusion in fresh material is at hand. However on
the basis of the shape of the pleurocystidia and the fact that they often show a
yellow internal body as revived in Melzer's, P. fraxinophila and P. madeodisca
appear to be closely related-a conclusion substantiated further by their aspect,
habit, habitat, and time of fruiting.
Material examined. Michigan: Ammirati 1439, 2002; Potter 9464; Smith
36356, 5-22-68. New York: Peck's type.
111. Psathyrella canadensis A. H. Smith, sp. nov.
Pileus 1.5-3.5 cm latus, obtusus vel convexus, demum late convexus, tenuiter
fibrillosus, ad marginem appendiculatus, cinnamomeo-brunneus demum argil