The North American species of Psathyrella.

1972]

PSATHYRELLA

365

at pileus surface but colored cinnamon near the subcuticular region, becoming
paler on standing. Hyphae of subcuticular zone vinaceous-cinnamon in KOH,
walls smooth to minutely roughened. Clamps present.
Type locality. Kentville, Nova Scotia, Canada.
Habit and habitat. On a well rotted birch log, October.
Distribution. Known only from the type locality.
Observations. This species lacks the wedge-shaped spores (in face view) of
P. fuscofolia, in fact the spores are almost identical with those of P. confertissima.
It differs from both in the structure of the cuticle of the pileus.
338. Psathyrella albocinerascens A. H. Smith, sp. nov.
Pileus 1-4 cm latus, plano umbonatus vel late convexus, glaber, pallidus
demum violaceo-griseus; lamellae latae, subdistantes, albidae demum triste fulvae; stipes 3-6 cm longus (3-)5-8(-10) mm crassus; dissiliens, candidus, ad
basem copiose myceliosus; velum nullum; sporae 7.5-9x4-4.5 ~; pleurocystidia
36-52 x 8-14 (-17) A, fusoide ventricosa, obtusata; fibulae adsunt. Typus. Smith
78300 (MICH); legit prope Highlands, Michigan.
Illust. Text Figs. 729-732.
Pileus 1-4 cm broad, convex with an incurved margin, expanding to broadly
umbonate or plane and sometimes the margin recurved, glabrous, moist, hygrophanous, when young whitish to watery gray, becoming drab as the spores mature
and the surface at times dusted with them, when fading becoming white, when
dried white to grayish. Context thin, fragile, white to watery gray, odor and taste
mild, FeSO4 not causing a color change.
Lamellae adnate but soon seceding, broad, subdistant to close, white when
young, soon near russet as the spores mature, edges even.
Stipe 3-6 cm long, (3-) 5-8 (-10) mm thick, equal or nearly so, hollow, splitting
lengthwise readily, arising from a mass of white mycelium reminding one of an
oozonium, white over all from youth to age and naked except for a slight pruina
near the apex; veil absent.
Spore deposit dark chocolate in color. Spores 7.5-9 x4-4.5 u, smooth, apical
pore present but inconspicuous under oil, in face view ovate to elliptic, in profile
subovate to obscurely inequilateral, color in KOH dark chocolate-color, in
Melzer's reddish tawny to bay, wall about 0.2 pt thick.
Basidia 4-spored, 26-32 x7-9 /u, narrowly clavate, hyaline in KOH, Pleurocystidia 36-52x8-14(-17) t, utriform (rarely) to obtusely fusoid (commonly)
or fusoid-ventricose (not as common), wall thin, smooth and hyaline in KOH;
other more versiform cells also present; subfusoid with wall slightly thickened
to 0.5,u near or in the apex and these often bifurcate or with a lateral protuberance
near apex; some broadly subfusoid and with yellowish walls 0.5 /p thick (in KOH);
rarely some clavate to misshapen but otherwise like the broadly subfusoid cells.
Cheilocystidia as for the various types of pleurocystidia (versiform) but more
with yellow walls in KOH. Caulocystidia versiform as for pleurocystidia but
mostly some variation of clavate to cylindric.
Pileus cuticle a staggered palisade of clavate-pedicellate to inflated-pedicellate
cells 15-40 tu wide, walls smooth, thin and hyaline in KOH or Melzer's. Hyphae
of context including subcutis hyaline and smooth as revived in KOH. Clamps
present. Subhymenium orange-rusty (in thick sections) as revived in Melzer's;
the pileus trama merely weakly yellowish.
Type locality. Highland, Michigan.