The North American species of Psathyrella.

19721

PSATHYRELLA

391

ventricosae, confertae; stipes 4-7 cm longus, 3-5 mm crassus, pallidus, glaber;
velum sparsum; sporae 8-10.5x4-5 /x; pleurocystidia in "KOH" ochracea, 32 -46 (-56) x 9-20 A, late fusoide ventricosa, obtusa; fibulae adsunt. Typus. WellsKempton 6/13/64 no. 1 (MICH); legit prope Anchorage, Alaska.
Pileus 2-4 cm broad, convex becoming broadly convex or finally plane, margin
connivent at first, but in age sometimes uplifted, obtusely umbonate in some,
hygrophanous, fading from disc outward, when moist dark yellow-brown (raw
umber), buff colored to dull orange-cinnamon on disc when faded, glabrous overall except for the marginal area which at first is decorated with minute patches
or squamules of veil remnants at times concentrically arranged, glabrescent by the
time the pileus is fully expanded, shiny in appearance when glabrous and still
moist, margin only faintly striatulate when moist. Context concolorous with
surface, thin (1.5 mm approximately), tapering to pilear margin, moderately
fragile, odor and taste pleasantly fungoid.
Lamellae pallid in buttons, very soon becoming brown (about concolorous with
the moist pileus), finally blackish brown, adnate to adnexed, ventricose and
moderately broad (up to 5 mm), close to crowded, margins concolorous.
Stipe 4-7 cm long, 3-5 mm thick, brittle, equal, or near the base enlarged
slightly, pallid and unchanging, apex pruinose-punctate, glabrous below, smooth,
polished in age; veil pallid and fibrillose, thin, all traces often lost by maturity.
Spore deposit violaceous-fuscous. Spores 8-10.5 x4-5 I, smooth, apical pore
distinct and apex truncate, shape in face view elliptic to obscurely ovate, in profile mostly obscurely inequilateral, color in KOH chocolate soon going to dark
chocolate, in Melzer's dark rusty brown, wall about 0.3 Pu thick.
Basidia 4-spored, short-clavate, hyaline in KOH, 16-22x7-10 t/. Brachybasidioles not differentiated. Pleurocystidia 32-46(-56) x 9-20 /, broadly fusoidventricose with short neck and obtuse apex, varying to merely fusoid-ventricose,
wall as revived in KOH thin to slightly thickened (-0.5 /A) and in most weakly
dull yellowish in KOH, smooth. Cheilocystidia similar to pleurocystidia but some
with refractive particles in the interior near the apex.
Gill trama of inflated cells, weakly yellow-brown in KOH and fading (as
revived). Pileus cuticle a layer of vesiculose cells 2-5 deep, their walls yellowish in KOH. Hyphae of the subcutis yellow-brown to rusty brown in KOH and
with yellow-brown incrustations-the latter as pigment deposits on some of the
lower cells in the cuticle as well (often at the angles of the cells). Clamps present.
Type locality. Near Anchorage, Alaska.
Habit and habitat. Gregarious to subcespitose on and around rotting wood,
moss and humus in a bog, mostly willow and cottonwood nearby, June.
Distribution. Alaska.
Observations. This species is readily distinguished by the degree of development of the veil, medium-sized spores, violet-fuscous spore deposit, short, fat
yellowish cystidia in KOH, the thick cuticle of the pileus and the vernal fruiting
period.
367. Psathyrella umbrosa A. H. Smith, sp. nov.
Pileus 1-3 cm latus, campanulatus vel convexus, glaber, pallide cinnamomeus
demum umbrosus; lamellae praeangustae, confertae, brunneolae demum fuscae;
stipes 2-5 cm longus, 1-3 mm crassus, albus demum brunneolus glaber; sporae
7-9 x 4-5 /A, in cumulis atratae; pleurocystidia 36-48 x 9-13 /u, fusoide ventricosa,