The North American species of Psathyrella.

1972]

PSATHYRELLA

101

Caulocystidia up to 140 x 12 p, elongate-utriform with flexuous sidewalls, hyaline
and smooth in KOH.
Pileus cuticle of somewhat inflated cells and the layer several cells deep,
pallid brownish (in KOH) to hyaline, content not distinctive; with filamentose
hyphae scattered over the surface and apparently originating from among the
cells of the cuticle. Hyphae of the trama hyaline in KOH, thin-walled and lacking
incrustations. No distinctive reactions noted in mounts made in Melzer's.
Type locality. Pole Mountain, near Laramie, Wyoming.
Habit and habitat. Solitary in swampy areas under brush or on decayed
wood of aspen, especially around beaver ponds.
Distribution. Idaho, New Mexico, Utah, Wyoming.
Observations. This is a large species with gray evident in the pileus before
the color changes occur which are associated with maturation of the spores. It
is close to P. subagraria in overall appearance, but the latter has pleurocystidia.
Material examined. Idaho: Smith 47188, 47305, 65848, 69094. New Mexico:
Barrows 124, 746, 1217, 1477, 1790, 1830, 2031, 3003. Utah: McKnight F131.
Wyoming: Kanouse 8-28-23; Kauffman 8-27-23; McKnight F8024; Smith 34526,
34675, 34730, 34744, 34900, 34903 (Type), 34919, 35003, 35334; Solheim 4697,
4717, 4718, 4754.
61. Psathyrella luteopallida A. H. Smith, sp. nov.
Pileus 8-20 mm latus, late convexus, ad marginem appendiculatus fibrillosus,
luteolus; lamellae confertae adnatae angustae albidae demum avellaneae; stipes
10-25 mm longus, 1-2 mm crassus, fragilis, albidus deorsum fibrillosus; sporae
9-12x5-6 u; fibulae adsunt. Typus. Sharp 20863 (MICH); legit prope Knox
County, Tennessee.
Pileus 8-20 mm broad, hemispheric becoming broadly convex to nearly plane,
rarely nearly fully expanded, margin appendiculate at first, surface otherwise
fibrillose moist and hygrophanous, when young pale yellow ("light ochraceousbuff" to pale ochraceous), when water soaked gray ("light mouse gray"), atomate
when faded. Context soft, thin and readily collapsing, white, odor and taste not
distinctive.
Lamellae close, adnate, narrow, white becoming "avellaneous" but pale tan
as dried, sometimes with a pinkish tint, edge fimbriate.
Stipe 10-25 mm long, 1-2 mm thick, equal slender, fragile, white over all,
striate and pruinose above, fibrillose to subscaly below, bulbilose at base in some,
hollow; veil white, fibrillose leaving remnants along the margin at first.
Spores deposit "hair brown." Spores 9-12 x 5-6 /, smooth, apical pore none,
shape in face view elliptic to obscurely ovate, in profile somewhat bean-shaped
to obscurely inequilateral, color in KOH grayish hyaline, not darkening appreciably, in Melzer's dingy ochraceous to weakly dextrinoid, wall thin.
Basidia 4-spored, 16-22 9-13 t, broadly clavate from a narrow pedicel,
rarely subglobose-more so toward the gill edge. Pleurocystidia absent. Cheilocystidia clavate to utriform to fusoid-ventricose with rounded apex, smooth,
thin-walled, hyaline and readily collapsing.
Gill trama interwoven, cells inflated, hyaline, smooth; subhymenium cellular.
Pileus cuticle of vertically elongate elliptic to angular cells in addition to subglobose type, all smooth, thin-walled and hyaline, cell content not distinctive.
Hyphae of subcuticular region hyaline and smooth-walled. Clamps present.
Type locality. Knox County, Tennessee.
Habit and habitat. Gregarious on soil and humus at edge of a lawn.
Distribution. Tennessee. Type studied.