The North American species of Psathyrella.

1972]

PSATHYRELLA

257

Spores 7-9 (-10) x 4-5 a, smooth, apical pore present as a small hyaline spot,
shape in face view elliptic to narrowly (slightly) ovate, some with a shallow
medial depression, in profile bean-shaped to obscurely inequilateral, color in
H20 mounts when fresh bright reddish brown, and chocolate-brown revived in
KOH, tawny in Melzer's, wall about 0.3 p thick.
Basidia 4-spored, 17-22 x 8-9 /, clavate, hyaline in KOH. Pleurocystidia and
cheilocystidia similar, abundant 38-65 x 9-18 /, fusoid-ventricose, the apex obtuse
to subacute varying to broadly rounded (and cystidium utriform), the wall
usually thickened to 1-1.5 A, apex often slightly incrusted, hyaline in HO2
mounts when fresh, dull vinaceous-brown to avellaneous (the color in the wall
in old revived material), in Melzer's no distinctive reaction in the cell content
or wall (the cystidia reviving better in Melzer's than in KOH). Caulocystidia
abundant, in bunches, 32-60 x8-17/t, fusoid-ventricose with obtuse to rounded
apex and the latter incrusted with amorphous material, the walls thin and hyaline,
content hyaline; some smooth broadly ventricose cells with thin entirely smooth
walls also present and up to 22 t broad.
Gill trama regular, the hyphae reddish brown in water mounts when fresh and
dingy brown to nearly hyaline when revived in KOH. Pileus having a cuticle of
hyaline vesiculose cells 30-60 / wide, the walls smooth and thin, cell content
not distinctive in KOH or Melzer's. Hyphae of the context reddish brown in
water mounts when fresh, when revived in KOH pale dingy brown with a
vinaceous tinge. Clamp connections present. No distinctive reaction on any tissue
in mounts in Melzer's.
Type locality. Jackson Guard Station, Olympic National Park, Washington.
Habit and habitat. Scattered to gregarious on old wood and debris of alder
and cottonwood.
Distribution. Michigan, Oregon, Washington.
Observations. The vinaceous to avellaneous tint to the pleurocystidia is a
somewhat variable feature in that not all the cystidia on a gill show it, but it
is a feature of a number of species in various groups as indicated in the present
work. In the present instance it is correlated with thickened walls, but in other
species showing it, the cystidia are often only slightly thickened and a veil is
present.
Material examined. Michigan: Potter 8566; Smith 32451, 32467, 32468, 57131.
Oregon: Smith 23818. Washington: Smith 13454, 13744, 14118 (Type), 14276,
14685,14686, 30230, 30231.
215. Psathyrella solitaria A. H. Smith, sp. nov.
Pileus 8-15 mm latus, subplanus, glaber, vel ad marginem sparse fibrillosus,
pallide fulvus vel sordide cinnamomeus; lamellae confertae, angustae pallide
cinnamomeae demum cacaocolor; stipes 3-4 cm longus, 1-2 mm crassus, albidus,
floccoso-fibrillosus vel squamulosus, glabrescens; sporae 7.5-9 x 4.5-5.5 /; pleurocystidia 38-46 x 9-15 /, fusoide ventricosa, ad apicerum obtusa vel late rotundata,
crassotunicata (0.5 /), maura cum "KOH" griseo-vinacea; fibulae adsunt. Typus.
Smith 20523 (MICH); legit prope Ann Arbor, Michigan.
Pileus 8-15 mm broad, convex becoming nearly plane, surface moist and
hygrophanous, at first with a few pallid to white fibrils along the margin from
the remnants of the veil, soon entirely glabrous, "ochraceous-tawny" to "Sayal