The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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veil of appressed white fibrils and with fibrils forming a fringe on the margin, soon
becoming entirely glabrous, surface moist and hygrophanous, at first dark rusty
brown ("Mars brown") soon ochraceous-tawny (paler) near marginal area, fading
to pale tan ("cinnamon-buff"). Context thin, concolorous with surface moist or
faded, fragile, odor and taste not distinctive.
Lamellae pallid buff when young, becoming dark rusty brown like the pileus,
adnate but soon seceding, close, margins whitish and minutely crenulate.
Stipe 3-5 cm long, 1.5-2.5 mm at apex, nearly equal, fragile, pallid in upper
region, soon dull honey-color to tan from the base upward, frosted-pruinose above,
lower down thinly coated with pallid fibrils from the veil, slowly glabrescent.
Spore deposit near "benzo brown" (lacking a red component). Spores 7-8.5 x
4-4.5(-5) a, smooth, apical pore indistinct (apex rounded), shape in face view
ovate to obscurely wedge-shaped, in profile obscurely bean-shaped to obscurely
inequilateral, color in KOH dark cocoa-color and remaining so, in Melzer's reddish
tawny, wall about 0.2 / thick.
Basidia 4-spored, 18-24x7-9 a, clavate, hyaline. Pleurocystidia 40-60 x
10-16 ju, fusoid-ventricose with obtuse to subacute apex, varying to subfusoid,
smooth, walls thin and hyaline, content not distinctive in either KOH or Melzer's.
Cheilocystidia like the pleurocystidia but smaller and more of them subfusoid;
clavate to saccate cells also present and 9-15 / broad. Caulocystidia similar to
pleurocystidia or larger, a small number broadly utriform and up to 20,/ wide,
many clavate to inflated-versiform, all types hyaline and thin-walled.
Cuticle of pileus of inflated cells 3-5 cells deep, the walls rusty brown in KOH
when fresh, when revived pale cinnamon. Tramal hyphae rusty cinnamon in KOH
and with incrustations. Clamp connections present. No distinctive reaction on
any tissue when revived in Melzer's.
Type locality. Hulbert, Michigan.
Habit and habitat. Cespitose-gregarious on a rotten hardwood log, July.
Distribution. Known only from the type locality.
Observations. This species features a thin outer veil of appressed fibrils, russet
coloration, large pleurocystidia rarely with a slight resinous incrustation over the
apex, broad gills, medium small spores, and a stipe which darkens from the base
up in addition to the key characters.
Stirps Minutisperma
Key to the Species of Stirps Minutisperma
1. Spores 4-5 X 2.5-3 u. 180. P. minutisperma.
1. Spores larger. 2
2. Growing on burned areas. 181. P. carbonicola.
2. Not as above. 3
3. Gills rich reddish chocolate-brown at maturity. 183. P. fibrillosipes.
3. Not as above. 4
4. Spores not truncate; on barren sandy soil. 407. P. parva.
4. Not as above. 5
5. Around decaying stumps and wood of hardwoods (see P. cornifericystis also).
182. P. pseudosenex.
5. Under larch; spores truncate. see 123. P. laricina.
180. Psathyrella minutisperma A. H. Smith, sp. nov.
Pileus 8-12 mm latus, conicus vel campanulatus, albido granulosus vel subfibrillosus, ad marginem albo denticulatus, glabrescens, melleus vel subspadiceus;