The North American species of Psathyrella.

1972] PSATHYRELLA 265
Observations. The large spores, numerous broadly rounded pleurocystidia, the
medium-sized stature, strong odor, pinkish tint when faded and veil absent or
rudimentary, along with the habitat are its distinguishing features.
Material examined. The type.
224. Psathyrella nezpercii A. H. Smith, sp. nov.
Pileus 5-12 mm latus, late convexus, glaber, fusco-brunneus, dein (ad marginem) demum incarnato-tinctus; lamellae subdistantes, latae, brunneolae demum
fusco-brunneae, ad acierum incarnatae; stipes 3-6 cm longus, 1 mm crassus,
deorsum brunneolus, sursum pallidus, glaber; sporae 14-16.5 x 7-8.5 IL; pleurocystidia 26-35 x 9-14 ju, ventricoso-rostrata vel fusoideo-ventricosa; fibulae adsunt.
Typus. Smith 65852 (MICH); legit prope Riggins, Idaho.
Illust. Text Fig. 512-514.
Pileus 5-12 mm broad, convex to obtusely conic becoming broadly convex,
surface moist, hygrophanous, glabrous, chocolate-brown moist, fading to fawn
color or avellaneous and later developing pinkish tones, surface irregularly rimose
in age. Context exceedingly fragile, lacking an odor or taste.
Lamellae subdistant, broad, adnate, seceding, pallid brownish becoming
chocolate-color and on the edges finally pinkish.
Stipe 3-6 cm long, about 1 mm thick, delicate, equal, brownish below, pallid
above, naked.
Spores 14-16.5 x 7-8.5 1, smooth, truncate from an apical pore, in face view
narrowly oval to subelliptic, in profile obscurely inequilateral to subelliptic, color
in KOH fuscous-brown ("mummy brown"), in Melzer's dark bay-red, wall 0.6 -0.8,u thick.
Basidia 4-spored, 24-30x 12-16,u, broadly clavate. Pleurocystidia scattered,
26-35 x 9-14 f, ventricose-rostrate to fusoid-ventricose, smooth, thin-walled,
hyaline; content as revived in KOH or Melzer's not distinctive. Brachybasidioles
present, 10-16 / wide. Cheilocystidia similar to pleurocystidia or vesiculose and
with yellowish walls as revived in KOH, content not distinctive in KOH or
Melzer's. Caulocystidia none.
Pileus cuticle a layer of vesiculose cells 1-2 deep, the walls hyaline and thin,
the content not distinctive. Tramal hyphae dingy cinnamon in KOH, the walls
smooth to very minutely roughened, the cell content not distinctive. Clamp connections present. No distinctive reactions on any tissue when mounted in Melzer's.
Type locality. Papoose Creek, Nezperce National Forest, Idaho, near Riggins.
Habit and habitat. Scattered on mud in a pasture, August.
Distribution. Idaho.
Observations. This species features an apparent lack of caulocystidia, presence
of brachybasidioles, lack of a veil, large spores, blackish spore deposit, small
pleurocystidia and gill edges becoming pinkish in age. The manner in which the
cuticle of the pileus breaks up is not regarded as important taxonomically. The
species appears to be close to P. potteri.
Material examined. Idaho: Smith 47272, 53656, 65852 (Type).
225. Psathyrella potteri A. H. Smith, sp. nov.
Pileus 1-2.5 cm latus, conicus vel campanulatus, glaber, cinnamomeo-fulvae;
lamellae latae, demum subdistantes, atratae; stipes 1.5-3 cm longus, 1-1.5
(-2) mm crassus, pallidus, sparse fibrillosus, glabrescens; sporae 12-14 x 7-8.5 u;