The North American species of Psathyrella.

1972]

PSATHYRELLA

277

10-15 u, saccate to clavate to fusoid-ventricose with broadly rounded apex, thinwalled and hyaline or wall yellow and in some the wall slightly thickened over
the apical region and yellowish, content not distinctive. Caulocystidia similar to
cheilocystidia or more versiform and variable in size.
Gill trama regular, rusty brown fading to nearly hyaline (in KOH). Pileus
trama with a cuticle of vesiculose cells to clavate cells vertically arranged and
staggered to form a layer 1-2 cells deep, the walls yellowish to hyaline in inflated
part and brownish ochraceous in the pedicels. Hyphae of the subcuticular region
rusty brown in KOH and showing conspicuous patches of incrusting plates or
patches of pigment especially near the septa. Clamp connections present.
Type locality. West Albany, New York.
Habit and habitat. Gregarious in sandy soil on dunes, etc. associated with
dune grasses.
Distribution. Michigan, New York, Texas.
Observations. Psathyrella ammophila (Dur. & Lev.) Orton, the European
counterpart of this species, apparently has slightly wider spores. A critical restudy
of both should be made. I have not observed a veil on the Michigan collections,
but admittedly very few buttons have been found. P. flexispora Wallace & Orton
has pleurocystidia but is otherwise very close to P. arenulina.
Material examined. Michigan: Bailey 7-28-51; Fischer 10-16-05; McCrea
F70; Potter 6667, 6770, 6783, 6886, 9280; Smith 21861, 32666, 36129, 41848,
42994, 51187, 73028. New York: Peck, Albany County. North Carolina: Mazzer
4724. Texas: Wright 11-22-59.
236. Psathyrella debilis Peck, Bull. Torrey Club 23: 418. 1896.
Illust. Text Figs. 534A.
Pileus 1.5-3.5 cm broad, campanulate to umbonate, surface striate nearly to
the umbo, in dried material somewhat sulcate along the margin but not typically
plicate-striate, subhyaline to whitish, becoming grayish and when dried more or
less pale ochraceous-buff. Context membranous and fragile.
Lamellae adnate, thin, narrow, crowded, whitish when young, becoming black.
Stipe 5-8 cm long, 2-3.5 mm thick, slender, weak, flexuous, never erect, hollow,
white.
Spores 12.5-16 (-17) x 5.5-7,u, smooth, apical pore distinct and apex of spore
showing a narrow truncation, shape in face view elliptic to slightly ventricose or
ovate, in profile subelliptic to obscurely inequilateral varying to obscurely beanshaped, color in KOH bister to "mummy brown" (blackish-brown) on standing,
near bister when first revived, many pallid spores in the mount (of the type); in
Melzer's bay-red, wall about 0.6 g thick as revived in KOH.
Basidia 4-spored, 24-28 x 9-10 gj, hyaline in KOH, clavate. Brachybasidioles
14-16x 10-12 A, more or less saccate from a broad base. Pleurocystidia none.
Cheilocystidia scattered, more or less fusoid-ventricose, 25-34 x 9-12 (-15) /, apex
obtuse to subacute, hyaline and thin-walled.
Gill trama made up of vesiculose hyaline cells, subhymenium cellular and
hyaline. Pileus trama hyaline, the cuticle of vesiculose enlarged cells and hence
the difference between these and the cells of the tramal hyphae not very striking,
the walls thin, smooth, hyaline, and the cell content not distinctive. Clamps
present.
Type locality. Rooks County, Kansas.
Habit and habitat. On damp ground attached to decaying leaves.