The North American species of Psathyrella.

1972]

PSATHYRELLA

43

Key to the Stirpes of Subgenus Psathyroides
1. Pileus hispid-squamulose; pleurocystidia with amyloid content (check mature
specimens); stipe 1-2 mm thick. stirps Hispida.
1. Not with above combination of features. 2
2. Cuticular hyphae of pileus (those forming the squamules) lacking a colored
content when mounted in KOH. 3
2. Hyphae forming squamules over pileus having ochraceous to yellow-brown
content when revived in KOH. stirps Lepidota.
3. Spores in face view shaped like the flat side of a kernel of corn. stirps Hirtosquamulosa.
3. Spores not truncate at the base in face view as in above choice. stirps Lacrymabunda.
Stirps Hispida
This stirps is limited to Psathyrella species with hispid-squamulose pilei and
with at least some pleurocystidia with amyloid content. Only the type species is
known, but it is not yet established that it occurs in North America.
9. Psathyrella hispida Heineman, Bull. Royal Soc. Bot. Belg. 74: 146. 1942.
Illust. 1. c. fig. 2.
Pileus about 15 mm broad, slightly fleshy, hemispheric-campanulate then
convex-expanded, margin straight then spreading, extending beyond the gills,
scarcely hygrophanous, dark grayish brown, covered with numerous fascicles of
blackish fibrils which on the disc may be more or less upright, toward the
margin they are more appressed.
Lamellae crowded to close, broad (about 2.5 mm), ventricose, at first sinuateadnate, then from the spreading of the pileus broadly notched and with a decurrent tooth, about concolorous with the pileus, edge whitish, finely denticulate.
Stipe 2-3 cm long, 1-2 mm thick, equal, flexuous, shiny white or toward the
base brownish, pruinose above, covered to near apex with fibrils similar to those
on pileus or lower down these arranged into minute scales, narrowly tubular and
fairly tough.
Spores 6.5-7x4.5-5,u, deep purple-brown in deposit, clear brown under the
microscope, violaceous in concentrated H2SO4, face view subangular and truncate
at the base, in profile view showing a plage area that is depressed and an apical
hump, germ pore distinct.
Basidia 4-spored, about 30 x 7 p. Pleurocystidia rare, ventricose and broadly
rounded at apex, often with resinous adhering material, violaceous in Melzer's,
not metachromatic in cresyl blue, 30-50 x 13-20 t. Cuticle of pileus of vesiculose
cells not forming a palisade, filamentous hyphae arising from among them.
Type locality. Belgium.
Habit and habitat. Among mosses on wet ground.
Distribution. Belgium.
Observations. In addition to having amyloid pleurocystidia this species differs
from P. hirtosquamulosa in having typical pigmentation of the spores for the
genus as these are revived in KOH, i.e., some shade of cocoa-color at first. This
species is included here because I suspect it occurs in North America but I have
no specimens as vouchers. If my suspicions are correct great care should be taken
to study carefully all small solitary-occurring basidiocarps having squamulose
pilei. These are the ones that are usually "lost" in large collections of species
when mushrooms are abundant, or they spoil before one can study them.