The North American species of Psathyrella.

1972 ]

PSATHYRELLA

329

Gill trama of inflated hyaline cells with thin, smooth walls. Pileus having a
cuticle of vesiculose hyaline cells 2-3 deep, walls thin, smooth, hyaline and readily
collapsing, cell content not distinctive. Context hyphae hyaline in KOH, cells
greatly enlarged and thin-walled. Clamp connections present.
Type locality. Europe.
Habit and habitat. Scattered on grassy ground and on soil in moist places.
Distribution. Michigan, Utah.
Observations. The pleurocystidia are variable in their occurrence in this
species, but the relationships of the fungus nevertheless are in this group. In
Smith 78106 some pleurocystidia measured up to 18 /u broad. This collection
represents a slender delicate form growing under a dense growth of weeds.
Material examined. Michigan: Kauffman 7-22-12; Smith 9565, 43070, 74433,
74436, 78106. Utah: McKnight F1009, F1565.
300. Psathyrella filamentosa A. H. Smith, sp. nov.
Pileus 5-12 (-15) mm, convexus vel planus, glaber, demum sulcatus, spadiceus,
ad marginem demum incarnatae; contextu fragilissimus lamellae confertae, latae,
adnatae, melleibrunneae, demum atro-brunneae, ad acierum demum incarnatae;
stipes 2-5 cm longus, circa 1 mm crassus deorsum brunneus, sursum pallidus;
sporae 11-14x 5.5-7 I; pleurocystidia 43-58x 10-17 /, fusoide ventricosa, obtusata vel subacuta; fibulae adsunt. Typus. Smith 78074 (MICH); legit prope
Vanderbilt, Michigan.
Illust. Text Figs. 640-642.
Pileus 5-12(-15) mm broad, obtusely conic expanding to convex or nearly
plane, surface glabrous, moist, hygrophanous, margin becoming sulcate at times
in age (but not plicate-striate), a medium date brown to dark honey brown when
moist, pallid to dingy tan when faded and later often developing pink tints.
Context almost paper-like in thinness, extremely fragile, odor not distinctive.
Lamellae close, broad, adnate, dingy honey tan becoming blackish brown,
edges whitish or in age pink at times.
Stipe 2-5 cm long and 1 mm thick, equal, delicate, brown over basal part,
pallid near apex, naked or at apex faintly pruinose.
Spores 11-14 x 5.5-7 ju, smooth, apex truncate from a broad pore, shape in face
view ovate to elliptic, in profile obscurely inequilateral, color in KOH dull rusty
brown quickly becoming blackish brown to dark chocolate, dark tawny to near
amber brown in Melzer's, wall about 0.7, thick.
Basidia 4-spored, 10-12 g broad, clavate. Pleurocystidia 43-58 x 10-17 g,
fusoid-ventricose with apex obtuse to subacute and some with adhering granules
(in KOH). Cheilocystidia fusoid-ventricose, 34-45x 10-15 /u, fusoid-ventricose,
apex acute to subacute, yellow clavate to vesiculose cells 10-18x8-13,u also
present on the gill edge.
Hyphae of the subcuticular zone of the pileus dark to medium rusty brown in
KOH and with distinct pigment incrustations. Cuticle of inflated cells 1-2 deep
and with clay color to pale tawny walls as revived in KOH, fading to hyaline
in places, walls smooth and thin. Clamp connections present.
Type locality. Fisherman's Road, Cheboygan County, Michigan.
Habit and habitat. Scattered on mud flats in a drying up swamp, September.
Distribution. Known only from the type locality.
Observations. The stipe is almost filamentous and exceedingly delicate. The
species is a "satellite" of P. anaglaea. Actually P. superiorensis, P. anaglaea and