The North American species of Psathyrella.

1972]

PSATHYRELLA

113

5. Pleurocystidia (some of them) soon lilac gray to vinaceous brown tinted in KOH
mounts, apex lacking adhering granules in KOH. (see also 117. P. indecorosa).
75. P. avellaneifolia & variants.
5. Pleurocystidia hyaline or if a few cystidia become colored in KOH, most have
granules adhering around or over the apex. 6
6. Pileus white when young. see 103. P. pseudolactea & 353. P. acuticystis.
6. Pileus brown when young. 7
7. Spores 6-7 X 3-4.5 gu. (see 107. P. sequoiae and 122. P. iterata also).
76. P. paradoxa and variants.
7. Spores 4.5-6 u long. 8
8. Stipe 8-17 mm long, about 1 mm thick. 77. P. subfilipes.
8. Stipe 10-20 cm long, 3-5 mm thick; growing in dense clusters. 78. P. confertissima.
71. Psathyrella alaskaensis A. H. Smith, sp. nov.
Pileus 5-50 mm latus, obtusus demum late convexus, glaber, subcinnamomeus
vel olivaceo-brunneus, ad marginem appendiculatus; lamellae pallidae demum
griseo-brunneae, latae, confertae; stipes 30-50 mm longus, 3-6 mm crassus,
subalbidus, sursum pruinosus; sporae 5-6 X 3-3.5 A; pleurocystidia 33-52 x 9-16 /,
crassotunicata (0.5 /), obtusa vel late rotundata; fibulae adsunt. Typus. WellsKempton 9/27/65 no. 5 (MICH); legit prope Anchorage, Alaska.
Pileus 5-50 mm broad, convex, becoming broadly convex, margin connivent at
first, glabrous, hygrophanous, fading from the disc out, when moist watery
reddish brown to watery olive-brown (finally), fading to ochraceous-tan and
then unpolished to atomate; margin appendiculate, opaque when moist. Context
concolorous with the pileus surface, thin (about 2 mm) at the disc, fragile, odor
and taste slightly sweetish-fungoid but not distinctive.
Lamellae pallid to pale tan becoming a medium dark grayish brown, adnate,
close, moderately broad (up to 6 mm), edges whitish crenulate.
Stipe 30-50 mm long, 3-6 mm broad at apex, equal, white to pale ivory,
brittle and tubular, dry, pruinose above, with appressed longitudinal fibrils below,
base white-floccose; veil white, fibrillose-arachnoid, moderately well developed
but the remnants soon evanescent.
Spore deposit chocolate-brown (dark cocoa-brown as air dried). Spores
5-6 x 3-3.5 pA, smooth, apical pore present but obscure, shape in face view oblong
to elliptic, in profile suboblong to obscurely inequilateral or slightly bean-shaped,
color in KOH dark cocoa-brown slowly becoming dark chocolate-color, in Melzer's
tawny-red, wall thin.
Basidia 4-spored, 16-20 X 5-7 /, clavate. Pleurocystidia 33-52 x 9-16 U, narrowly fusoid-ventricose with obtuse apex toward base of gill and broadly fusoidventricose to utriform (rarely elliptic and 30-40 p long) toward the gill edge, wall
slightly thickened (0.5 u) and refractive in KOH over midportion, smooth, content
not distinctive. Cheilocystidia 28-38 (-46) x 9-15 t, mostly bluntly fusoid to
fusoid-ventricose, wall smooth and refractive in KOH, content not distinctive.
Caulocystidia versiform and mostly on veil hyphae appressed to the stipe, wall as
in pleurocystidia, located mostly near the apex of the stipe.
Pileus cuticle a palisade of inflated cells with the upright arrangement fairly
distinct but becoming obscured by maturity; walls smooth and hyaline; cell
content not distinctive. Hyphae of subcutis vinaceous-cinnamon to cinnamon in
KOH, fading somewhat, walls smooth, no distinctive reaction evident on any
tissue when mounted in Melzer's. Clamps present.
Type locality. Anchorage, Alaska.
Habit and habitat. Cespitose on decayed wood along disturbed edge of a road,
September.