The North American species of Psathyrella.

1972]

PSATHYRELLA

185

Habit and habitat. Scattered to gregarious on humus and buried twigs in a
lawn.
Distribution. Michigan and New York.
Obseravtions. In the Michigan collection (by L. H. Pennington 9-11-07), the
spores are dull bay-red in Melzer's and clamp connections are present though
difficult to locate because they are very small. The species is not a Coprinus, at
least brachybasidioles are not present.
142. Psathyrella delicatella A. H. Smith, sp. nov.
Pileus 5-10 mm latus, campanulatus, demum late conicus, copiose albofibrillosus; glabrescens, pallidus demum avellaneus dein vinaceo-brunneus; lamellae
confertae, latae, subhepaticolor; stipes 3-5 cm longus, circa 1 mm crassus, fibrillosus ad basem myceliosus; sporae 12.5-15 x6.5-8 /j; cheilocystidia 28-36x
12-18 I, clavata vel utriformia; fibulae adsunt. Typus. Brooks 1619 (MICH);
legit prope Geary County, Kansas.
Illust. Text Figs. 317-319.
Pileus 5-10 mm broad, obtusely campanulate becoming broadly conic, surface
at first densely covered by a coating of superficial whitish (when dried, yellow)
outer veil fibrils, young pilei pallid to avellaneous, when mature glabrous and near
"army brown" (vinaceous brown). Context very thin and delicate.
Lamellae close, broad, ascending-adnate, reddish chocolate color when mature,
edges slightly fimbriate.
Stipe 3-5 cm long, about 1 mm thick, equal or nearly so, whitish, (no evidence
of much discoloration in dried material), covered by very pale yellowish (as
dried) outer veil remnants, base conspicuously mycelioid with more or less
radiating fibrils or a mat of fibrils.
Spores 12.5-15 x 6.5-8 /, smooth, apical pore distinct and spore apex truncate,
shape in face view with a somewhat pointed apiculate end, otherwise elliptic to
ovate, in profile somewhat to obscurely inequilateral (plage area typically
flattened), color in KOH date brown (bister before maturity, near "mummy
brown" when mature), in Melzer's very dark bay-red, wall about 0.8 pt thick.
Basidia 4-spored, sterigmata very fine, clavate and 10-14 /u broad, hyaline in
KOH. Brachybasidioles present, 12-22 JL broad, hyaline and readily collapsing.
Pleurocystidia not seen. Cheilocystidia scattered to numerous, 28-36x 12-18 /,
fusoid-ventricose with scarcely any neck and apex broadly rounded to obtuse,
wall thin, smooth and hyaline, content not distinctive. Caulocystidia 50-80 x
15-25 /A, subventricose with obtuse apex, thin-walled, hyaline, some 40-65x
8-14 / and tapered to an obtuse apex; some clavate and 15-20 p/ broad.
Gill trama hyaline in KOH. Pileus trama hyaline or nearly so in KOH.
Cuticle of pileus a layer of vesiculose cells several deep and the individual cells
very thin-walled and hyaline. Clamp connections present.
Type locality. Geary County, Kansas.
Habit and habitat. Gregarious in a sunflower patch.
Distribution. Known only from the type locality.
Observations. The non-striate pileus, presence of brachybasidioles, pronounced
outer veil, lack of pleurocystidia, the large spores and the very large numerous
caulocystidia are distinctive.
Material examined. Kansas: Brooks 1618, 1619 (Type).