The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Type locality. Near Longmire, Mt. Rainier National Park, Washington.
Habit and habitat. On debris among willows and cottonwood, single to
gregarious.
Distribution. Known only from type locality.
Observations. In addition to the rather fibrous stipe (for a Psathyrella) the
spores are wider than usual for their length. The inclusion in the pleurocystidia
recalls that of the group of species around P. delineata. It does not show in KOH
in revived material so I would not class the cystidia as "chrysocystidia."
Material examined. Washington: Smith 29757 (Type).
128. Psathyrella subeinerascens A. H. Smith, sp. nov.
Pileus 1-3 cm latus, demum convexus, ad marginem appendiculatus, sparse
fibrillosus, glabrescens; lamellae confertae, latae, brunneolae demum violaceogriseae; stipes 3-5 cm longus, 3-6 mm crassus, deorsum demum griseus, albofibrillosus, glabrescens; sporae 7-9 x 4-5 x 5-6 u; pleurocystidia 40-56 x 10-18 p,
fusoide ventricosa, obtusa: fibulae adsunt. Typus. Smith 34502 (MICH); legit
prope Pole Mountain, Laramie, Wyoming.
Illust. Text Figs. 296-299.
Pileus 1-3 cm broad, obtuse to convex, the margin appendiculate at first with
the submembranous remains of the partial veil, universal veil very thin to absent,
surface moist and hygrophanous, cinnamon-brown fading to cinnamon-buff.
Context very thin and fragile.
Lamellae broadly adnate, close, pallid brownish becoming dark grayish brown
(near "benzo brown").
Stipe 3-5 cm long, 3-6 mm thick, equal, white to pallid, white-fibrillose from
remains of a partial veil but glabrescent, gray in the base in age.
Spores, 7-9x4-5x5-6 /, smooth, some very slightly flattened, apical pore
inconspicuous but apex broadly truncate, shape in face view ovate to subelliptic,
in profile view slightly bean-shaped to obscurely inequilateral, color as revived
in KOH cocoa-color soon becoming dark chocolate-color, in Melzer's bay-red,
wall about 0.4,u thick.
Basidia 22-30x8-10 /z, 4-spored, hyaline in KOH, clavate. Pleurocystidia
abundant 40-56x10-18 /u, fusoid with subacute to obtuse apex (rare), fusoidventricose with obtuse apex (common), and subutriform (not common), all with
walls thin, smooth and hyaline, content not distinctive. Cheilocystidia 20-30 x
9-15 /A, clavate to vesiculose, smooth, thin-walled, hyaline. Stipe with hyaline
cortex-hyphae which are minutely roughened (?) as seen in KOH.
Pileus with a cuticle of vesiculose to variously inflated cells which in KOH
have pale ochraceous to pale cinnamon walls, the latter smooth and thin. Hyphae
of the pileus and gill trama vinaceous brown in KOH, incrusted or with wall
thickenings especially at or near the septa. Clamp connections present. No
distinctive reactions noted on any tissue as mounted in Melzer's.
Type locality. Pole Mountain, near Laramie, Wyoming.
Habit and habitat. Scattered on muck near beaver ponds.
Distribution. Known only from type locality.
Observations. This species is a "satellite" of P. velibrunnescens but grows on
muck, has a white veil, and pleurocystidia varying from subelliptic-pedicellate to
fairly narrowly fusoid.