The North American species of Psathyrella.

1972]

PSATHYRELLA

341

abundant, thin-walled, 28-39 x 9-15 /u, fusoid-ventricose to clavate, subelliptic or
vesiculose. Caulocystidia in patches, similar to cheilocystidia but more variable
in size.
Gill trama vinaceous in KOH, color fading slowly, incrustations present on
hyphae of the central area but not the subhymenium. Pileus trama persistently
rather dark vinaceous-brown to pale cocoa-color in KOH, hyphae incrusted.
Cuticle of pileus a palisade of large (35-50 x 10-25 /) ellipsoid to cystidioid thinwalled hyaline cells with the apex of the cystidioid cells broadly rounded, cell
content not distinctive. Clamp connections present. No distinctive reaction noted
on any tissue as revived in Melzer's.
Type locality. Edwards, Kansas.
Habit and habitat. Subcespitose on wet soil (mud).
Distribution. Known only from the type locality.
Observations. The thin veil, large spores, short and broad pleurocystidia and
short stipes make this a recognizable species.
312. Psathyrella parvicystis A. H. Smith, sp. nov.
Pileus 10-20 mm broad, latus, obtusus vel convexus demum late convexus, ad
marginem fibrillosus, glabrescens valde striatus fuscus demum avellaneus;
lamellae confertae, latae, pallide avellaneae demum atro-brunneae; stipes 6-8 cm
longus, 1-1.5 mm crassus, albidus, deorsum leviter fibrillosus glabrescens; sporae
12-16(-18) x 6-8 /t; pleurocystidia rara 28-40x 10-15 /, fusoide ventricosa, ad
apicerum acuta; fibulae adsunt. Typus. Smith 18305 (MICH); legit prope West
Branch, Michigan.
Illust. Text Figs. 673, 674.
Pileus 10-20 mm broad, obtuse to convex, becoming broadly convex, surface at
first with scattered fibrils along the margin from the thin white veil, soon the
surface entirely glabrous, conspicuously translucent-striate when moist, somewhat
sulcate when faded, color dull wood brown when moist, hygrophanous and pale
avellaneous when faded. Context very thin and fragile, odor and taste not
distinctive.
Lamellae close, broadly adnate, not readily seceding, narrow to moderately
broad, pallid avellaneous becoming blackish brown, edges even.
Stipe 6-8 cm long, 1-1.5 mm thick, very fragile and delicate, white, pruinose
above, lower portion at first with scattered fibrils from the veil but soon glabrous,
attached to the substratum by a white mycelial mat.
Spores 12-16(-18) x6-8 /, smooth, with a distinct apical pore and apex
truncate, shape in face view elliptic, ovate or slightly ventricose, in profile
obscurely inequilateral to subelliptic, color mummy brown (blackish brown) with
the more immature spores various shades of date brown, in Melzer's bay-brown,
wall about 1.3 p thick.
Basidia 4-spored, 20-24x10-12 /t, capitate to clavate, hyaline in KOH.
Brachybasidioles differentiated by late maturity. Pleurocystidia very rare,
28-40 x 10-15 fI, fusoid-ventricose with acute apex, wall thin, smooth and hyaline,
content not distinctive in KOH. Cheilocystidia similar to pleurocystidia and also
many clavate to ellipsoid cells 18-24x7-12 / present, the walls of the cells
(especially the bases) and the supporting hyphae often yellow in KOH, walls thin
and smooth. Caulocystidia fusoid-ventricose to clavate or vesiculose, apex mostly
acute, wall thin, smooth and hyaline, variable in size but not over 50 x 15,/.
Gill trama regular, the cells large and somewhat interwoven, dull rusty brown
in KOH but with a faint tinge of cocoa-color at first, subhymenium cellular.