The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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203. Psathyrella naucorioides A. H. Smith, sp. nov.
Pileus 9-30 mm latus, late convexus, glaber, pallidus demum sordide vinaceobrunneae; lamellae angustae, pallidae, brunneolae demum vinaceo-brunneae;
stipes 1-3 cm longus, 1-2.5 mm crassus, hyalinus; velum nullum; sporae 5-6X
3.5-4 u, in "KOH" subhyalinae; pleurocystidia 38-47 x 12-17 g, late fusoidea,
acuta, crassotunicata (~_3 / crassa); fibulae adsunt. Typus. Smith 73467
(MICH); legit prope Priest Lake, Idaho.
Illust. P1. 70, fig. a & c; Text Figs. 473-476.
Pileus 9-30 mm broad, broadly convex with an inrolled margin, in age nearly
plane with an even to slightly crenulate margin, surface glabrous and hygrophanous, when young pallid at least on the margin, with the central area
avellaneous, later wood-brown to "Verona brown" (dingy vinaceous-brown),
striatulate when moist. Context thin and cartilaginous-fragile, odor and taste
mild, no reaction with FeSO4.
Lamellae close, narrow, horizontal, pallid then brownish and finally dull
vinaceous-brown ("army brown"), edge even.
Stipe 1-3 cm long, 1-2.5 mm thick, equal, cartilaginous, with a whitish tuft
of mycelium at the base, hyaline, and naked over all or soon watery-pallid,
becoming dusted from the spores, faintly pruinose near apex; veil absent on
even the smallest buttons.
Spore deposit chocolate-brown. Spores 5-6 x 3.5-4 /, smooth, apical pore not
evident, shape in face view elliptic to slightly ovate, in profile obscurely inequilateral to obscurely bean-shaped, color in KOH pale smoky ochraceoushyaline, in Melzer's faintly reddish to pale ochraceous, wall thin.
Basidia 15-20 x 6-7.5 u, 4-spored, hyaline in KOH, projecting about half their
length when sporulating. Pleurocystidia abundant, 38-47 x 12-17 u, broadly
fusoid-pointed, apex often incrusted as revived in KOH, wall up to 3, thick
near apex, hyaline, content of cell not distinctive. Cheilocystidia similar to
pleurocystidia or vesiculose to saccate. Caulocystidia cylindric to vesiculose,
walls yellowish when fresh or revived in KOH, thin to thickened, some similar
to pleurocystidia and also many intermediate types present, walls hyaline to
yellow.
Cuticle of pileus a layer of vesiculose cells and clavate cells 1-2 deep, walls
smooth, hyaline to yellowish in KOH, about 0.2-0.3 A, thick; hyphae of the subcuticular region smooth and merely weakly ochraceous in KOH, flushed orange
to reddish or paler in Melzer's as is the subhymenium at times. Clamp connections present.
Type locality. Upper Priest River, Boundary County, Idaho.
Habit and habitat. Cespitose to gregarious on cottonwood logs.
Distribution. Idaho, Washington.
Observations. In P. naucoria the spores are flattened somewhat, and the
pileus when young is cinnamon-brown. The difference between P. camptopoda
and P. naucorioides in spore color parallels that between P. spadicea and P.
sublateritia.
Material examined. Idaho: Harrison 6304; Smith 73467 (Type), 73627.
Washington: Smith 49012, 49099.
Section Cystidiosae A. H. Smith, sect. nov.
Sporae in "KOH" subcinnamomeae; pleurocystidia crasso-tunicata vel tenuitunicata, ad apicem saepe subgranulosa. Typus. Psathyrella cystidiosa.