The North American species of Psathyrella.

1972]

PSATHYRELLA

73

species the pleurocystidia were not observed to have thickened walls and they
typically are more obtuse and have more granular material adhering around the
apex, and of course there is a striking difference in pigmentation of the pileus.
Material examined. California: Lanphere 61; White 358. Oregon: Smith
55579 (Type).
34. Psathyrella barrowsii A. H. Smith, sp. nov.
Pileus 2-6 cm latus, convexus vel umbonatus, glaber, spadiceus; lamellae
confertae angustae demum sublatae, pallidae demum sordide vinaceo-brunneae;
stipes 7-14 cm longus, 3-7 mm crassus, deorsum strigosus et subradicatus, albidus,
sursum pruinosus, deorsum subsquamulosus; annulus gossypinus, albidus, in
exsiccati avellaneus; sporae 7.5-9x4-5 /; pleurocystidia 33-46 x 9-15 /1, fusoide
ventricosa, ad apicerum obtusa, fibulae adsunt. Typus. Barrows 1307 (MICH);
legit prope Santa Fe, New Mexico.
Pileus 2-6 cm broad, broadly obtuse to convex-umbonate, expanding to plane
or nearly so or retaining a slight umbo, surface glabrous, moist, hygrophanous,
color when young date brown but becoming lighter (in yellow-brown series) before
fading to cartridge buff or pale tan. Context thin, fragile, concolorous with the
surface when moist or faded, taste and odor not distinctive.
Lamellae adnate (bluntly or with a decurrent tooth), close, equal, narrow to
moderately broad, pallid when young, near "bone brown" (dark vinaceous-brown)
in age, edges pallid.
Stipe 7-14 cm long, 3-7 mm thick, equal or narrowed to a somewhat rooting
base which is strigose, white and pruinose above, lower down (beneath the
annulus) with patches or a zone of veil fibrils or in some with a second annulus;
basal area not distinctly discoloring; annulus thick, cottony, collar-like with a
flaring upper limb, white but drying avellaneous.
Spores 7.5-9x4-5,u, smooth, apical pore present but apex only obscurely
truncate, color in KOH dark cocoa-color slowly changing to dark chocolate-color,
in Melzer's dark reddish tawny, shape in face view ovate with the base in many
somewhat truncated (as in P. subtruncatispora), varying to broadly subelliptic,
in profile obscurely broadly-inequilateral, wall about 0.3 / thick.
Basidia 4-spored, 14-20x6-8 /i, clavate, hyaline. Pleurocystidia scattered,
33-46x9-15 /, broadly subfusoid with obtuse apex, fusoid-ventricose with an
obtuse apex or a few ventricose-subcapitate (not truly utriform), wall thin, smooth
and hyaline, content of cell not distinctive. Cheilocystidia similar to pleurocystidia
or clavate to saccate and 24-35x8-15 L, walls hyaline to yellowish in KOH.
Pileus cuticle a layer of vesiculose cells 2-3 deep, the cells thin-walled, hyaline
to ochraceous in KOH. Hyphae of trama in subcuticular region vinaceous in KOH
and pigment in the walls and some incrusted near the septa. Clamps present.
Type locality. Santa Inez Mountains, New Mexico.
Habit and habitat. Under aspen, gregarious.
Distribution. Colorado, New Mexico, Wyoming.
Observations. This species has shorter pleurocystidia of a different shape, and
smaller spores than P. solheimii var. sanjuanensis. In both, the annulus is thick,
cottony, and dried avellaneous in color. It is distinct from P. kauffmanii in having
a thick annulus and a significant number of spores truncated at the base (as seen
in face view).
Material examined. Colorado: Smith 51809, New Mexico: Barrows 411, 437,
1008, 1307 (Type). Wyoming: Solheim 3636, 3656, 3710, 4383, 4728.