The North American species of Psathyrella.

1972]

PSATHYRELLA

227

6. Stipe 8-11 cm long; pleurocystidia all hyaline in KOH (see P. roothaanensis
also). 194. P. undulatipes.
7. Scattered on decaying wood of hardwoods. 188. P. senex.
7. On soil or conifer wood and duff or wet leaves. 8
8. Spores 5-6 / wide (see P. depauperata also). 9
8. Spores 3.5-5 /u wide. 10
9. Pleurocystidia 46-65 X 9-13,. 189. P. cascadensis.
9. Pleurocystidia 32-46 X 10-16 /u. 190. P. affinis.
10. Hyphae in subcuticular region of pileus incrusted. 191. P. fibrillosa.
10. Hyphae in subcuticular region smooth to minutely roughened. 192. P. payettensis.
184. Psathyrella cornifericystis A. H. Smith, sp. nov.
Pileus 1.5-3.5 cm latus, late convexus vel expanso-umbonatus, sparse fibrillosus glabrescens, ad marginem saepe plicatus; spadiceus vel pallide spadiceus;
lamellae 5-7 mm latae, demum ventricosae, pallidae demum melleae dein triste
violaceo-griseae; stipes 2.5-3.5 cm longus, 2-4 (-5) mm crassus, pallidus, fibrillosus
glabrescens; sporae 6-7.5 (-8) x 4-4.5 u; pleurocystidia 48-65x 8-12 p, anguste
fusoideo-ventricosa vel fusoide ventricosa, ad apicerum cum 1-3 processis; fibulae
adsunt. Typus. Smith 21384 (MICH); legit prope Ann Arbor, Michigan.
Illust. P1. 63, figs. a-b; P1. 91, fig. a; Text Figs. 418-421.
Pileus 1.5-3.5 cm broad, convex to obtusely conic, expanding to broadly convex
or finally nearly plane, somewhat umbonate at times, surface moist and hygrophanous, at first coated with superficial white fibrils but soon glabrous or merely with
silky fibrils adhering along the margin, margin fringed with fibrils at first but
soon naked and frequently plicate-crenate, margin straight at first, color evenly
"Saccardo's umber" or a little paler and near "snuff brown" fading to near
avellaneous but at times some finally changing to sordid honey color. Context
thin, fragile, concolorous with surface, very brittle, odor and taste not distinctive.
Lamellae broad (5-7 mm), horizontal, becoming ventricose, pallid to pale
honey yellow at first, nearly drab to dusky drab (dark violaceous-gray) in age,
edges conspicuously white-fimbriate.
Stipe short, 2.5-3.5 cm long, 2-4 (-5) mm thick, fragile, hollow, equal or
slightly enlarged above, white to whitish and not discoloring, or merely watery gray
beneath the fibrils, more or less covered with white fibrils, base often radiatestrigose.
Spores 6-7.5 (-8) x 4-4.5 [, smooth, apical pore inconspicuous and spore apex
only obscurely truncate, shape in face view broadly ovate to broadly elliptic, in
profile obscurely inequilateral to subelliptic, color in KOH dull cocoa-color soon
changing to a medium dark chocolate-color, reddish tawny in Melzer's, wall about
0.2, thick.
Basidia 17-24 x 5-7 JL, 4-spored, hyaline in KOH. Pleurocystidia very abundant, 48-65x8-12 A, narrowly subfusoid to fusoid-ventricose, apex obtuse to
subacute and in many with 1-3 protuberances or fingerlike projections more or
less well developed, wall thin, smooth and hyaline, cell content not distinctive in
KOH or in Melzer's. Cheilocystidia 36-45 x 8-11 p, basically similar to pleurocystidia; also small clavate to vesiculose cells present. Caulocystidia abundant
26-62x 6-15 p, versiform (Fig. 419), wall thin, smooth and hyaline, cell content
not distinctive.
Gill trama interwoven, hyaline in water mounts when fresh and hyaline as
revived in KOH, or if pale vinaceous-brown in young caps fading quickly. Pileus
having a cuticle of clavate-pedicellate and vesiculose cells mixed, their walls
slightly yellowish in water mounts when fresh, dingy pale vinaceous to dingy pale