The North American species of Psathyrella.

1972]

PSATHYRELLA

431

spores), not undergoing autodigestion but in age pallid after spores have been
discharged.
Stipe 6-9 cm long, 4-5 mm thick, equal, hollow, firm and rigid (for the genus),
naked to the more or less pruinose apex, pallid over all (not darkening below);
veil rudimentary.
Spores 8-11 x 5-6 t, smooth, apex only obscurely or not at all truncate, in face
view broadly elliptic to ovate to somewhat angular-ovate at times, in profile
obscurely inequilateral to somewhat inequilateral, color near cocoa-brown at first,
soon bister or darker revived in KOH.
Basidia 4-spored, projecting 2 different lengths when sporulating. Basidioles
broadly clavate. Pleurocystidia 50-65 x 14-22 A, ventricose-pedicellate with
broadly rounded smooth apex, hyaline, thin-walled, smooth. Cheilocystidia not
distinct in age (the gill edge somewhat gelatinous) in young pilei basidioles and
a few cheilocystidia resembling pleurocystidia present, the cheilocystidia 37 -72 x 15-29 p, fusoid-ventricose to capitate.
Pileus cuticle a layer of greatly inflated more or less short cells hyaline in
KOH and with no distinctive content. Clamps present but often difficult to
demonstrate.
Habit, habitat and distribution. Solitary to scattered near edge of a road,
Ann Arbor, Michigan, Oct. 21, 1971, Smith 81042.
Observations. This species is amply distinguished by the relatively firm stipe,
radially splitting pileus as in many Coprini, the large broadly rounded pleurocystidia, and clavate basidioles. The very slight veil is a significant feature but
not of great aid to the taxonomist. In mounts of chloral hydrate and water (2:1),
the regions of the gill edge where gelatinization was taking place became purple
after standing about a half hour.
This species indicates a distinct progression toward Coprinus in the manner in
which the pileus splits, but lacks brachybasidioles in the hymenium and no true
autodigestion takes place. Young basidiocarps might be mistaken for those of
Coprinus insignis Peck.
405. Psathyrella nimkeae A. H. Smith, sp. nov.
Pileus 1-2.5 cm latus, obtuse conicus, demum late conicus, glaber, nitens,
melleus demum melleo-griseus; fragilis; lamellae brunneolae, demum griseopurpureo-brunneae; stipes 3-5(-6) cm longus, 2-3 mm crassus, glaber, ad basin
strigosus, subradicatus, albidus demum sordidus; sporae 12-15 x 6-6.5 p; pleurocystidia 50-75 x 10-15 /A, fusoide ventricosa, valde pedicellata, subacuta. Typus.
Nimke 158 (MICH); Ann Arbor, Michigan, 12 Oct. 1971, ad lignam.
Pileus 1-2.5 cm broad, obtusely conic becoming broadly conic, surface glabrous, naked, shining, when moist dark honey-color becoming paler and grayer
before fading to whitish, not atomate, fading on disc first; no veil remnants
present. Context thin, fragile, pallid, odorless.
Lamellae pallid brownish, becoming gray-brown, then toned distinctly grayish
lilac, finally a dark dull purple brown, ascending-adnate, close, moderately broad,
edges pallid.
Stipe 3-5(-6) cm long, 2-3 mm thick, nearly equal, more or less naked down
to the crooked white-strigose, rooting base, whitish and not darkening appreciably
on aging.
Spore deposit dark purple brown. Spores 12-15 x 6-6.5 t, smooth, apical pore
distinct and lens-shaped, shape in face view narrowly elliptic to oblong, in profile somewhat bean-shaped to cymbiform or obscurely inequilateral; color near