The North American species of Psathyrella.

1972]

PSATHYRELLA

47

not distinctive or merely weakly brownish in KOH, not amyloid. Cheilocystidia
similar to pleurocystidia and also as hyaline inflated cells. Caulocystidia found
only as scattered clavate to vesiculose cells.
Pileus cuticle a layer of vesiculose cells several deep and with smooth hyaline
thin walls, cell content not distinctive in KOH or Melzer's. Trama hyaline in
KOH, hyphal walls smooth. Veil hyphae with smoky ochraceous homogeneous
content as revived in KOH, the hyphae 6-12 l wide and both short and long cells
present, with a distinct tendency to disarticulate. Clamp connections present. No
tissue reacting distinctively when revived in Melzer's.
Type locality. Roxbury Creek, Chippewa County, Michigan.
Habit and habitat. Gregarious on rotten hardwood logs.
Distribution. Michigan.
Observations. The collection was made by Dr. Roy Watling, Sept. 18, 1969
(Smith 78178). This species should differ from P. lepidota in having basally
truncated spores and a bitterish unpleasant taste as well as in the tendency for
the outer veil hyphae to have short cells and a tendency for the cells to disarticulate. This latter feature might be regarded as a forerunner to the subgenus
Cystopsathyra.
Material examined. Michigan: Ammirati 3225; Hoseney 1402; Smith 50044,
78178 (Type), 78192.
13. Psathyrella olivaceogrisea A. H. Smith, sp. nov.
Pileus (2-)2.5-4.5 cm latus, subovatus vel convexus, demum late convexus vel
obtuse umbonatus, olivaceo-brunneus, fibrillosus vel fibrilloso-squamulosus; sapor
tarde subamarus; lamellae pallidae demum griseo-brunneae, ventricosae, latae,
subdistantes; stipes 3-5(-6) cm longus, 3-5(-6) mm crassus, deorsum olivaceobrunneus, fibrillosus vel squamulosus; sporae 8-10 x 4.5-6.5 /,; ad basem subtruncatae; pleurocystidia 40-50 x 13-20 ft, ad apicerum late rotundata, intus cum
globuli; hyphae epicuticularum intus olivaceo-brunneae. Typus. Wells-Kempton
8-15-63 no. 5 (MICH); Alaska.
Illust. Text Figs. 26-28.
Pileus (2-) 2.5-4.5 cm broad, subovate to convex, the margin connivent at first,
becoming broadly convex to nearly plane, sometimes with a low obtuse umbo,
moderately dark olive-brown in button, disc remaining olive-brown to olive but
the margins paler to gray-brown or (at maturity) pale olive-ochraceous-gray, dry,
unpolished, subvirgate to appressed patchy-scaly in buttons, surface fibrils and
squamules becoming separated over marginal area as pileus expands, scales more
or less evanescent in age and surface then merely fibrillose, or scales more persistent around the disc; margin usually splitting in age. Context translucent-pallid
when moist, opaque and white when faded, thin, pliant to somewhat fragile, odor
not distinctive, taste becoming slightly bitter slowly.
Lamellae pallid whitish becoming grayish brown and finally dark fuscousbrown, narrow, ventricose and moderately broad at maturity, close becoming
subdistant.
Stipe 3-5 (-6) cm long, 3-5 (-6) mm thick at apex, equal or enlarged downward,
olive-brown and fibrillose as in the pileus at first, when elongated dry and silkyshining from scattered appressed longitudinal fibrils, apex often faintly pruinose,
lower third of stipe often with patches of olive-brown veil remnants variously
distributed; partial veil white and fibrillose and not leaving an annulus when it
breaks.