The North American species of Psathyrella.

1972]

PSATHYRELLA

339

convex or plane, at first covered by a weft of white outer veil fibrils but all traces
of this soon gone, chocolate-brown when young and fresh, grayer as spores mature,
fading to pallid and then very atomate, in drying becoming avellaneous to wood
brown with disc tinged cinnamon. Context very thin and fragile, odor none.
Lamellae close, adnate, narrow, dull brown becoming vinaceous-brown and
finally dark purplish brown, when dried near hair brown to fuscous, edges even.
Stipe 6-8 cm long, 1.5-2 mm thick, equal, fragile, white and scarcely discolored
in age but dingy tan as dried, at first with scattered fibrils but soon glabrescent.
Spores 12-16 x 5.5-7 /, smooth, apical pore present but apex scarcely truncate,
shape in face view narrowly elliptic to oblong, in profile obscurely inequilateral
to narrowly subelliptic, color in KOH soon blackish brown, in Melzer's reddish
tawny, wall about 0.5 g thick.
Basidia 4-spored, clavate-capitate, 26-30 x 9-13 a, hyaline in KOH. Pleurocystidia 42-65 x 10-16 /, fusoid-ventricose the apex acute, wall usually refractive
and 0.3-0.6 M thick (in KOH), hyaline, content not distinctive. Cheilocystidia
more or less similar to pleurocystidia. Pileus cuticle 1-2 cells deep, walls pale
ochraceous to hyaline and thin. Hyphae of subcuticular region rusty brown in
KOH and with pigment incrustations and wall thickenings. Clamps present.
Type locality. Usk, Pend Oreille County, Washington.
Habit and habitat. On mud, under spruce, September.
Distribution. Known only from the type locality.
Observations. The spores are those of P. gracilis but the dark brown pilei and
thin veil along with the refractive walls of the pleurocystidia distinguish it. The
color of the dried basidiocarps is also distinctive. In P. fontinalis pinkish tints
develop on the faded pileus and the young gills are white at first.
310. Psathyrella subolivacea A. H. Smith, sp. nov.
Pileus (1-)2-4(-5) cm latus, late convexus vel subplanus, glaber rugulosus,
subfulvus vel spadiceus, dein olivaceo-brunneus, lamellae demum subdistantes,
latae (3-4.5 mm), pallide argillaceae, demum "fuscous"; stipes 5-8 cm longus,
1-2 mm crassus, glaber; sporae 12-15x6.5-8 a; pleurocystidia 40-60x9-16 j,
fusoide ventricosa ad apicerum acuta; fibulae adsunt. Typus. Smith 11042
(MICH); legit prope Dexter, Michigan.
Illust. P1. 81, fig. b; Text Figs. 665-668.
Pileus (1-)2-4(-5) cm broad, obtusely conic to convex, becoming broadly
convex or nearly plane, surface smooth to slightly rugulose, glabrous and moist,
color variable ("cinnamon-brown" to "ochraceous-tawny" to "tawny-olive" when
young, becoming "Dresden brown" to "snuff brown" to "sepia" or "olive-brown"
before fading to pinkish buff or "pale olive-buff"), the umber cast developing as
the spores mature. Context thin, watery brown, fragile, odor and taste not
distinctive.
Lamellae close but becoming subdistant, 18-22 reach the stipe, bluntly adnate,
lamellulae in 3 tiers, broad (3-4.5 mm), pallid to "pinkish buff" when young,
becoming darker brown and finally "fuscous" or with more of a purplish sheen,
edges pallid.
Stipe 5-8 cm long, 1-2 mm thick, strict, cartilaginous, tubular, equal, at first
with scattered fibrils from the very rudimentary veil or veil apparently absent,
apex pruinose, soon glabrous and polished, translucent in age and becoming sordid
toward the base, base faintly mycelioid at times.
Spores 12-15 x 6.5-8 gt, smooth, with a small apical hyaline pore but apex not