The North American species of Psathyrella.

1972]

PSATHYRELLA

127

Clamp connections present. No distinctive reactions on any tissue when mounted
in Melzer's.
Type locality. Ithaca, New York.
Habit and habitat. Scattered to gregarious on moist ground in woods, late
summer and fall, especially in elm swamps.
Distributions. Michigan, New York, Ohio, Oregon, Pennsylvania.
Observations. Previously I used the name P. artemisiae for this species, but
the present concept of that species in Europe now embraces some other fungus.
Atkinson's type checked well with my material so his name is used here. A neotype needs to be selected for the European P. artemisiae, but that is not possible
in the present work. Atkinson's species is actually most closely related to
P. uliginicola from our western mountains. As happens in nearly every case of
a pair of closely related species, ecological differences are apparent. Atkinson's
is adapted to the rich humus of moist woods; in southeastern Michigan it is found
most frequently in elm swamps often under Impatiens (jewel weed), whereas in
the Rocky Mountains, P. uliginicola occurs on wet soil under aspen, usually downstream from a beaver dam. In P. subagraria, occasional basidiocarps show very
few pleurocystidia, so at times one may key collections into section Candolleana.
Material examined. Michigan: Ammirati 1283, 3437; Hoseney 230; Kauffman
9-13-07,10-13-26; Pennington 9-11-07; Potter 5101, 5102, 5175, 5215, 8819, 8971,
9087; Shaffer 2613; Smith 33-1115, 1453, 1479, 5026, 6244, 7723, 18899, 18947,
20295, 20430, 28661, 32020, 61397, 65848, 67349, 75319, 78265. Ohio: Smith 78324,
5-28-37. Oregon: Smith 18199. New York: Atkinson's type. Pennsylvania:
Henry 4198.
82. Psathyrella seminuda A. H. Smith, sp. nov.
Pileus 2-4 cm latus conicus demum campanulatus, glaber, appendiculatus
cinnamomeo-brunneus; lamellae confertae, adnatae, latae, dilute brunneae demum
cinnamomeo-fulvae; stipes 3-6 cm longus, 2-3(-4) mm crassus fragilis deorsum
floccosus glabrescens, ad basem demum sordide brunneus; sporae 8-9.5 X 4.5 -5.3 5-6 A; pleurocystidia 48-60x 10-20 /, fusoide ventricosa obtusa vel subcapitata; fibulae adsunt. Typus. Smith 34091 (MICH); legit prope University of
Michigan Biological Station, Cheboygan County, Michigan.
Illust. P1. 42, figs. a, c; PI. 43, fig. a; Text Figs. 207-209.
Pileus 2-4 cm broad, obtusely conic to campanulate, expanding to broadly
campanulate to nearly plane, with or without an obtuse umbo, surface glabrous,
veil remnants only near or on the margin which is at first appendiculate from
patches of the submembranous to fibrillose veil, surface glabrous, moist and
hygrophanous, dull cinnamon to cinnamon-brown at first when fresh, when faded
near cinnamon-buff or paler. Context brownish, thin, fragile, odor and taste not
distinctive.
Lamellae close, adnate, moderately broad, pallid brownish to near cinnamonbuff and finally dark reddish brown.
Stipe 3-6 cm long, 2-3 (-4) mm thick, equal or nearly so, hollow, fragile, lower
portion slightly fibrillose from broken veil, soon glabrescent, glabrous above veil
zone, apex slightly pruinose, pallid at first but soon brownish at least in the lower
portion, slightly paler than the pileus when properly dried.
Spores 8-9.5 x 4.5-5.3 x 5-6,u, slightly compressed to terete, smooth, apical pore
present but not affecting the contour of the spore apex, shape in face view ovate to
elliptic, in profile obscurely inequilateral to obscurely bean-shaped, color in KOH