The North American species of Psathyrella.

1972]

PSATHYRELLA

287

Basidia 4-spored, 10-14 x9-10 u, nearly elliptic in optical section, hyaline
in KOH. Brachybasidioles present at maturity. Pleurocystidia rare to scattered,
similar to cheilocystidia. Cheilocystidia clavate to ventricose with short neck
and broadly rounded apex, hyaline in KOH, smooth, readily collapsing. Cuticle
of the pileus of inflated cells, the layer one cell deep, the walls dull cinnamon
at the base or in the pedicel (if pedicellate). Hyphae of the context not reviving.
Type locality. City Park, New Orleans, Louisiana.
Habit and habitat. Gregarious to cespitose on rotten wood and humus.
Distribution. Louisiana.
Observations. The presence of brachybasidioles, if indeed they can be properly so designated in view of the ellipsoid to subellipsoid basidia, the slight
veil and the medium-small spores are its most distinguishing features. In spore
features it seems very close to P. candolleana but the hymenial elements along
with the cinnamon walls in the bases of the cuticular cells distinguish it. From
the information available from the type, the species appears to be a variant
ambiguous between P. hymenocephala and P. candolleana.
250. Psathyrella byssina (Murrill) A. H. Smith, comb. nov.
Atylospora byssina Murrill, Mycologia 10: 20. 1918.
Psathyra byssina (Murr.) Murrill. Mycologia 10: 33. 1918.
Pileus 5-10 mm broad, strongly convex to plane, not umbonate, surface varying
from pinkish gray to brown tinged with pink, glabrous, nearly smooth, margin
entire, concolorous. Context very thin and fragile.
Lamellae adnate, crowded, rather broad, becoming dark purplish brown or
almost black.
Stipe 1.5 cm long, less than 1 mm thick, filiform, pallid or rosy-isabelline
smooth, glabrous, attached to the substratum by a very conspicuous radiating
mass of tomentum which is evidently white when fresh but slightly yellowish in
dried specimens.
Spores ellipsoid, smooth, 6.4-7.8 x 4.5-5 A, very pale purplish brown under the
microscope (Murrill), chocolate-gray when revived in KOH, apical pore present
(no additional details were obtainable). The type could not be found and the
Johnston collections (no. 330 and 420) are in very poor condition.
Type locality. Rio Piedras, Puerto Rico.
Habit and habitat. Gregarious on decayed logs.
Distribution. Puerto Rico.
Observations. The small pale spores, basal mat of myelium, lack of a veil,
and broad gills for such a small fungus distinguish it. It should be redescribed
from fresh material.
251. Psathyrella murrillii A. H. Smith, nom. nov.
Atylospora cubensis Murrill, Mycologia 10: 23. 1918. (non P. cubensis Murr.,
Mycologia 10: 27. 1918.)
Psathyra cubensis (Murr.) Murrill, Mycologia 10: 33. 1918.
Illust. Text Fig. 546.
Pileus 1-1.5 cm broad, convex to expanded and slightly depressed, surface
glabrous, hygrophanous, pale chestnut, paler when dry, margin faintly striate,
concolorous. Context thin and delicate.
Lamellae adnexed, crowded, subventricose, pallid to purplish brown, entire
and concolorous on the edges.