The North American species of Psathyrella.

1972]

PSATHYRELLA

429

present in the apex; wall smooth, thin and slightly refractive in some; hyaline in
KOH. Cheilocystidia similar to pleurocystidia or less rostrate (or merely clavate).
Cuticle of pileus a layer of vesiculose cells several deep, with ochraceous-hyaline
thin walls. Trama vinaceous cinnamon in KOH but soon fading. Clamps present.
Habit, habitat and distribution. Collected on soil in a grassy area at a rest
station, south of Grasmere, Highway 51, Owyhee county, Idaho. It was near a
creek with sagebrush nearby; E. Trueblood 3543.
Observations. This species is distinct by its desert habitat, the very broadly
ventricose pleurocystidia with refractive granules in the neck near the apical
region as revived in KOH, and distant gills. It is approximately like P. candolleana in stature.
(See) 394. Psathyrella griseopallida, Trueblood 4505
Pileus 2.5-4 cm broad, convex expanding to plane, surface glabrous, moist and
hygrophanous, the usual dingy cinnamon brown moist and when faded pale dingy
brownish but soon dusted black from spores; no evidence of a veil noted on the
pileus. Context thin and fragile.
Lamellae at maturity broad, nearly subdistant, adnate, blackish to blackish
brown, edges even.
Stipe 4-6 cm long, 2-4 mm thick, equal or at base slightly enlarged, hollow,
fragile, white and drying whitish except where dusted with spores, very thinly
fibrillose from a rudimentary veil; no evidence of discoloration per se.
Spore deposit blackish. Spores 7-10 x 4-5 /, smooth apical germ pore distinct,
some spores appearing truncate, in face view ovate to elliptic, in profile obscurely
bean-shaped to obscurely inequilateral, blackish brown in KOH.
Basidia 4-spored. Pleurocystidia 30-54x10-15 u, fusoid-ventricose (rarely
clavate), apex obtuse varying toward subacute, thin-walled, smooth, with some
internal refractive granules in neck in many. Cheilocystidia mostly of small
clavate to vesiculose pedicellate cells with ochraceous walls in KOH, others
present resembling pleurocystidia but smaller.
Cuticle a layer of inflated cells 3-5 deep, walls weakly ochraceous in KOH.
Hyphae of subcuticular region vinaceous brown as revived in KOH but not
distinctly incrusted. Clamps present.
Habit, habitat and distribution. On soil in grass under aspen, Juniper Mountain, Owyhee County, Idaho, June 9, 1971, Trueblood 4505.
Observations. The type was from under oak in southern California, and the
Trueblood collection was from under aspen, but both areas are semiarid and do
not present features sufficiently divergent to justify taxonimic emphasis. The
more frequently ovate spores in face view, their slightly darker color, and the
presence of only a rudimentary veil are the distinctive features of this variant
but do not seem too contrasting when compared to the type.
(See) 48a. Psathyrella incerta var. pygmea A. H. Smith, var. nov.
Pileus 1.5-3(-4) cm latus, obtuse conicus, ad marginem appendiculatus,
floccoso fibrillosus, glabrescens, pallide melleus deinde pallidus vel ad centrum
ochroleucus; fragilis; lamellae pallidae demum griseo-lilaceae, confertae angustae,
adnatae, secedentes; stipes 2-5 cm longus, 1.5-2.5 mm crassus, fragilissimus, albus,
albofibrillosus, glabrescens; sporae (4-5.5 x 3-3.5) 7-8 x 4-4.5 (8-9 x 4-5) ju; basidia tetraspora. Pleurocystidia nulla. Cheilocystidia 28-42 x 10-15 fL, clavata vel