The North American species of Psathyrella.

392

MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

obtusa, vel (rare) utriformia; fibulae adsunt. Typus. Barrows 1416 (MICH);
legit in Sangre de Christo Mountains, New Mexico.
Pileus 1-3 cm broad, obtusely conic expanding to obtusely campanulate or
convex, some nearly plano-umbonate, margin appressed at first, glabrous, moist
and hygrophanous, pale dingy cinnamon becoming umber as the spores mature,
fading to pallid but drying to nearly "Sayal brown" (dingy cinnamon). Context
thin, fragile, odor and taste not distinctive.
Lamellae very narrow, crowded, adnate-seceding, dingy brownish becoming
fuscous from the spores but drying dingy cinnamon (slightly darker than the
pileus), edges even.
Stipe 2-5 cm long, 1-3 mm thick, equal, fragile, white, becoming brownish in
age and when dried almost concolorous with the pileus, some slightly strigose at
the base.
Spore deposit blackish. Spores 7-9x4-5 a, smooth, apical pore small but
distinct and apex narrowly truncate, shape in face view elliptic to slightly ovate,
in profile obscurely inequilateral to subelliptic, color in KOH coffee-bean brown
slowly becoming dark chocolate, in Melzer's reddish tawny, wall about 0.3 / thick.
Basidia 4-spored, 20-30 x 8-9 /, clavate, hyaline. Pleurocystidia 36-48
9-13 /A, fusoid-ventricose, apex obtuse or (a few) utriform with apex subcapitate
and 6-8 p broad, hyaline, thin-walled, smooth, cell content not distinctive. Cheilocystidia clavate to subfusoid, 28-38x 9-15 p, apex rounded to obtuse, wall thin,
smooth and hyaline. Pileus cuticle a cellular layer 1-3 cells deep (some cells
up to 50 L wide), walls thin, smooth, hyaline to pale cinnamon. Hyphae of the
subcuticular zone dull pale rusty brown with pale tawny weak incrustations.
Clamps present.
Type locality. Sangre de Christo Mountains, New Mexico.
Habit and habitat. Densely gregarious on soil filled with rotten wood, August.
Distribution. New Mexico.
Observations. The densely gregarious manner of growth resembles that of
P. agrariella, but the gills are extremely narrow. A large number of basidiocarps
were compared on this point.
368. Psathyrella communis A. H. Smith, sp. nov.
Pileus 1-2.5(-3) cm latus, campanulatus vel late umbonatus, glaber, rufofulvus demum fusco-brunneus; lamellae confertae, latae, cinnamomeae demum
atro-brunneae; stipes 2-4 cm longus, 1.5-2.5 mm crassus, sursum pallidus, deorsum brunneus, glaber; velum nullum; sporae 7-8.5 x4-4.5 /u; pleurocystidia 36 -48 x 10-15 A, fusoide ventricosa acuta vel subacuta; fibulae adsunt. Typus. Smith
73951 (MICH); legit K. Harrison prope Priest River, Idaho.
Illust. Text Figs. 821-823.
Pileus 1-2.5 (-3) cm broad, obtusely conic expanding to broadly campanulate
or convex-umbonate, surface glabrous, moist, hygrophanous, dark rusty brown
becoming dark chocolate-brown, hygrophanous and fading to dingy tan, dingy
cinnamon as dried. Context dark colored, very thin and delicate, odor lacking.
Lamellae close, adnate, moderately broad, dingy cinnamon becoming dark
umber-brown to blackish, edges whitish and crenulate under a lens.
Stipe 2-4 cm long, 1.5-2.5 mm thick, equal, fragile, pallid above, dull tan
below, dull brown over all as dried, veil absent and stipe naked.
Spores 7-8.5x4-4.5 pA, smooth, apical pore distinct and apex with a minute