The North American species of Psathyrella.

1972]

PSATHYRELLA

281

13. Spores in KOH yellowish-avellaneous becoming avellaneous. 251. P. murrillii.
13. Spores in KOH dull cocoa-color becoming bister (dark brown). 252. P. tenuis.
14. Pileus white to pallid when young. 15
14. Pileus more distinctly pigmented. 16
15. Stipe white changing to reddish. 253. P. coprinoceps.
15. Stipe white and unchanging; growing on Roystonia. 254. P. roystoniae.
16. Lamellae crowded and arcuate. 255. P. cordobaensis.
16. Lamellae distant and adnexed. 256. P. dichroma.
240. Psathyrella diminutiva Murrill, Mycologia 10: 33. 1918.
Atylospora diminutiva Murrill, Mycologia 10: 19. 1918.
Pileus 6 mm broad, 2 mm high, hemispheric to broadly convex, with a small
umbo, not expanding, surface striate, uniformly avellaneous, glabrous, margin
straight, entire, concolorous. Context very thin and fragile.
Lamellae adnate, ventricose, distant, umbrinous to fuliginous, paler and entire
on the edges.
Stipe 5 mm long, 0.5 mm thick, curved, equal, slightly roughened, umbrinous.
Spores broadly lemon-shaped, smooth, subopaque, uniguttulate, purplish brown
under the microscope, about 5 x 4 u.
Type locality. Cinchona, Jamaica.
Habit and habitat. Scattered on fallen sticks.
Distribution. Known only from the type locality.
Observations. The above account is taken entirely from the original. No
details were obtained from the type. There is a chance that the species can be
recognized on the basis of the small lemon-shaped spores.
241. Psathyrella atricastanea (Murrill) A. H. Smith, comb. nov.
Drosophila atricastanea Murrill, Mycologia 10: 66. 1918.
Illust. Text Fig. 537.
Pileus 2-3 cm broad, broadly campanulate to subexpanded, surface strongly
hygrophanous, glabrous, dark chestnut, becoming pallid when dry except on the
disc, margin concolorous, not striate. Context very soft, delicate and fragile.
Lamellae adnate, crowded, rather broad, concolorous, cinnamon-brown when
dried.
Stipe 4-5 cm long, 2-4 mm thick, subcylindric, white, minutely floccose, hollow,
veil said to be lacking in even the young stages of the basidiocarps.
Spores 7-9x4-5 A, smooth, with an obscure apical pore, apex somewhat
truncated if lens-shaped pore-cover collapses, shape in face view ovate to elliptic,
in profile obscurely inequilateral to subelliptic, color in KOH weakly dingy
ochraceous but soon becoming pale avellaneous, in Melzer's dingy ochraceous to
pale tan, wall thin (-2 [ thick).
Basidia 4-spored, 15-18 x 8-10 u, hyaline in KOH. Pleurocystidia none.
Cheilocystidia scattered, 24-36x 10-14 /, ellipsoid to ventricose with broadly
rounded apex, hyaline in KOH, thin-walled and readily collapsing.
Gill trama poorly reviving and not distinctively colored in KOH. Pileus trama
of hyphae reviving poorly and merely dingy ochraceous in KOH; cuticle of
vesiculose cells 1-2 deep, the walls thin and smooth, yellowish to hyaline in KOH.
Clamps present, but difficult to demonstrate.
Type locality. Santiago de las Vegas, Cuba.
Habit and habitat. Gregarious from buried wood.
Distribution. Known only from the type locality.