The North American species of Psathyrella.

1972]

PSATHYRELLA

305

yellowish walls in KOH. Caulocystidia subcylindric to fusoid-ventricose with
obtuse apex, variable in size.
Gill trama hyaline to yellowish in KOH, of enlarged cells. Pileus trama of
hyphae with bister walls in KOH, slowly becoming paler yellowish brown on
standing; cuticle of pileus a layer one cell deep of voluminous (30-50 p wide)
hyaline vesiculose cells. Clamp connections present.
Type locality. Pinckney Recreation Area, Washtenaw County, Michigan.
Habit and habitat. Scattered on debris among sedges near edge of a bog.
Distribution. Michigan.
Observations. The cocoa-colored spores revived in KOH, the thin grayish veil,
the pleurocystidia intermediate between broadly rounded and obtuse, the vernal
fruiting period (May), and the pileus cuticle only one cell deep are distinctive.
Material examined. Michigan: Smith 21412 (Type), 32174.
274. Psathyrella lithocarpi A. H. Smith, sp. nov.
Pileus 2-4 cm latus, convexus vel campanulatus, corrugatus, pallide incarnatocinnamomeus; lamellae confertae vel subdistantes, angustae, pallidae demum
fuscae; stipes 5-9 cm longus, 2-4 mm crassus, albidus, fibrillosus demum glaber;
velum nullum; sporae 9-12 x 5-6.5,/; pleurocystidia 35-50 x 10-15 p, late fusoideoventricosa, ad apicerum rotundata; fibulae adsunt. Typus. Thiers 11801 (MICH);
legit prope Lake Chaleuma, California.
Pileus 2-4 cm broad, conic when young becoming broadly conic to (finally)
campanulate to broadly convex, surface glabrous, moist and hygrophanous, conspicuously corrugated, no veil fibrils in evidence anywhere; color pale buff to pale
pinkish cinnamon fading to pale pinkish buff or whitish. Context very thin and
fragile, taste and odor not distinctive.
Lamellae ascending-adnate, close to subdistant, narrow, whitish when young,
darkening to pale fuscous with whitish margins.
Stipe 5-9 cm long, 2-4 mm thick, equal, white and unchanging, long, slender,
surface appressed fibrillose to glabrous, stuffed becoming hollow; veil absent.
Spores 9-12 x 5-6.5 /, smooth, apex truncate from a broad apical pore, shape
in face view ovate, in profile somewhat to obscurely inequilateral, color in KOH
dark chocolate, in Melzer's bay-red, wall about 0.5 / thick.
Basidia 4-spored, clavate, 18-22 x 8-10 f. Pleurocystidia 35-50 x 10-15 u/, rare
to scattered, broadly fusoid-ventricose with rounded apex, wall smooth, thin and
hyaline, cell content not distinctive. Cheilocystidia similar to pleurocystidia.
Gill trama regular, hyphal walls smooth and weakly brownish in KOH. Pileus
trama not distinctively colored in KOH, hyphal walls smooth. Cuticle of pileus
a layer 3-5 cells deep, their walls smooth and thin. Clamps present.
Type locality. Lake Chaleuma, Santa Barbara County, California.
Habit and habitat. Gregarious near decomposed oak logs, November.
Distribution. California.
Observations. The dried basidiocarps remind one of slender pale specimens of
P. candolleana. The medium large spores, broadly rounded pleurocystidia, pale
color and lack of a veil are distinctive. Brachybasidioles appear to be present in
age but do not revive well.
Section Psathyrella
Subsection Mesosporae A. H. Smith, subsect. nov.
Sporae 9-12.5 / longae; pleurocystidia acuta vel obtusa.
Typus. Psathyrella acutoconica.