The North American species of Psathyrella.

1972]

PSATHYRELLA

175

Stipe 4-7 cm long, 3-6 mm thick, equal, rather firm and cartilaginous for the
genus, hollow, surface finely longitudinally striate in larger ones, naked, rarely
with veil remnants (these soon evanescent), white to pallid throughout and over
all, base not conspicuously mycelioid.
Spores 7.5-10x4.5-5 A/, smooth, apical pore present but obscure and apex not
truncate, shape in face view oblong to elliptic, in profile suboblong to obscurely
bean-shaped, color in KOH rich rusty cocoa-color slowly becoming dark chocolate, in Melzer's reddish tan to pale bay-red; wall about 0.3 /A thick.
Basidia 4-spored, clavate, 26-30x7-8 /A. Pleurocystidia scattered, 36-48x
9-13 1A, neck short and apex obtuse, or some narrowly nine-pin-shaped (with slight
apical enlargement); wall thin, smooth and hyaline. Cheilocystidia clavate to
vesiculose-pedicellate and hyaline in KOH, or shaped like the pleurocystidia.
Gill trama of interwoven somewhat inflated hyphae, central strand rusty
brown in KOH but soon fading, subhymenium cellular. Pileus cuticle a layer
of inflated cells 2-3 deep, walls smooth, thin and hyaline in KOH, some cells
pedicellate-clavate. Hyphae of subcuticular region rusty cinnamon in KOH,
slowly fading to dull ochraceous-tawny, pigment incrusted on the walls to some
degree. Clamp connections present.
Type locality. Sand's Basin, Owyhee County, Idaho.
Habit and habitat. Gregarious among native grasses in an area where cattle
were pastured, April.
Distribution. Known only from type locality.
Observations. The species is clearly a Psathyrella as the KOH reaction of the
spores indicates. Only well-pigmented spores were used in establishing the size.
As for many Psathyrella species, some evidence of partial sterility exists in the
type collection. A fair number of spores are weakly colored, measure 10-12x
6-7.5 A, and are broadly elliptic in face view. The veil is denticulate on the
margins of young or half-developed basidiocarps, but all traces may have vanished
by maturity. The species is apparently related to P. spadiceogrisea, P. verna and
P. atrofolia, but its ecology is very different and, of course, there is the usual
cluster of slight differences such as spore color, consistency of basidiocarps, pallid
naked stipe over all in most, and shape of the pleurocystidia.
132. Psathyrella verna A. H. Smith, sp. nov.
Pileus (1-)4-7 cm latus, late umbonatus vel subcampanulatus, glaber,
cinnamomeo-brunneus, ad marginem sparse fibrilloso-appendiculatus; lamellae
confertae, adnatae, latae (4-8 mm), albidae demum vinaceo-brunneae; stipes
8-14 cm longus, 3-8 mm crassus, pallidus, glabrescens; sporae 6.5-8(-9) x 4-4.5 x
4.5-5 /u; pleurocystidia 40-70 x8-15 Lu, fusoide ventricosa, obtusa vel subacuta;
fibulae adsunt. Typus. Smith 6207 (MICH); legit prope Manchester, Michigan.
Illust. P1. 55.
Pileus (1-)4-7 cm broad, ovoid to obtusely conic, becoming broadly umbonate
to subcampanulate, often nearly plane or with merely a decurved margin, margin
appressed against the stipe at first and sometimes flaring or slightly recurved in
age, striate, glabrous except for a fringe of evanescent fibrils along the margin,
moist, smooth or slightly wrinkled, "Mars brown" to "russet" or cinnamon-brown
or "buckthorn brown," hygrophanous, fading to "ochraceous-tawny" on the disc
and pale buff over the marginal area. Context moderately thin and not exceptionally fragile, watery brown moist, buff when faded, odor none or slightly
acidulous, taste mild.