The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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231. Psathyrella rudericola A. H. Smith, Jour. Elisha Mitchell Soc. 62: 186. 1946.
Pileus 1.5-3 cm broad, obtusely conic with an appressed margin at first, becoming conic-campanulate, rarely expanding further, a rudimentary veil present on
the smallest buttons, surface glabrous, moist, lubricous evenly "Natal brown"
when young (with a strong vinaceous tinge), fading to sordid gray or on the disc
watery pale sordid alutaceous, surface closely wrinkled-striate to near the disc
but not becoming plicate-striate as in Pseudocoprinus. Context very delicate, thin,
fragile, odor and taste none.
Lamellae "light vinaceous-fawn" (pale vinaceous) young, becoming pallid and
finally "hair brown" (dark drab), close, very narrow, ascending-adnate, edges
even.
Stipe 3-5 cm long, 1.5-2.5 mm thick at apex, hollow, fragile, white and
unchanging, pruinose above, slightly fibrillose below, glabrescent.
Spores 11-13 x 5.5-6.5 /, smooth, apical pore small but distinct and spore apex
only obscurely truncate, shape in face view narrowly elliptic to oblong, in profile
subelliptic, color in KOH bister (a medium date brown) when first revived in
KOH, slowly darkening to chocolate-color (with a gray cast), in Melzer's dull
reddish tawny, wall about 0.4 /A thick.
Basidia 4-spored, 20-26x10-12 u, dimorphic, hyaline in KOH. Brachybasidioles present, 18-26x 10-18 i. Pleurocystidia none. Cheilocystidia rare to
scattered, 36-48 x 10-15 I, clavate to fusoid-ventricose with obtuse apex. Caulocystidia not abundant, subcylindric to clavate as hyphal end cells.
Gill trama of irregularly arranged inflated cells, hyaline when revived in KOH
and in water mounts of fresh material. Pileus having a cuticle of inflated to
vesiculose cells with thin hyaline walls, pedicels of inflated cells also thin and
hyaline. Context of loosely arranged enlarged hyphal cells with hyaline metallicappearing laticifers scattered among them, hyaline in water mounts of fresh
material and when revived in KOH. Clamps present. No tissue with a distinctive
reaction in Melzer's.
Type locality. Ann Arbor, Michigan.
Habit and habitat. Gregarious to scattered on a compost pile of remains of
tropical plants.
Distribution. Known only from the type locality.
Observations. The lack of pleurocystidia and lack of distinctive color on the
subcuticular hyphae as revived in KOH along with more vinaceous-brown than
purplish tones in the pileus distinguish this species from P. barlae and P. bipellis.
It is close to P. conopilea but no setae were found on the pileus after repeated
attempts were made to find them.
232. Psathyrella atrospora A. H. Smith, sp. nov.
Pileus 1-2 cm latus, conicus, glaber, castaneus; lamellae confertae, latae,
fuscae demum atro-fuscae; stipes 4-5 cm longus, 2-3 mm crassus, albidus, deorsum brunneus; sporae 15-20(-21) X 7-9x 8-10 /; cheilocystidia 28-50x 10-30 u,
fusoideo-ventricosa vel ellipsoidea; fibulae adsunt. Typus. Thiers 25248 (MICH);
legit prope Mesa Grande, California.
Pileus 1-2 cm broad, obtusely conic expanding to convex or broadly conic,
surface glabrous moist and hygrophanous, chestnut-brown fading to amber brown,
striate on the marginal area when moist. Context thin and fragile, concolorous
with surface, odor and taste mild.