The North American species of Psathyrella.

1972] PSATHYRELLA 69
pinkish buff; margin at first appendiculate from particles of the white veil if
the annulus does not form. Context thin, fragile, pale tawny fading to pallid;
odor and taste not distinctive.
Lamellae close, moderately broad, nearly equal, pallid tan becoming chocolatebrown and drying dark cocoa-color, edges even.
Stipe 4-8(-10) cm long, 2-4 mm thick, equal, strict, naked except for a
superior annulus or if annulus lacking the veil fragments scattered along the
pileus margin, apex pruinose, white to pallid; annulus when present cottony,
whitish but in drying becoming avellaneous; base of stipe white-strigose and
basal region not appreciably discolored.
Spores 8-10.5 x 4.5-6 /, smooth, apical pore distinct and apex truncate, shape
in face view broadly to moderately broadly elliptic varying to ovate, in profile
obscurely inequilateral to subelliptic, color in KOH dark cocoa-color at first, in
15 minutes becoming dark chocolate-color, in Melzer's reddish tawny, wall about
0.4 L thick.
Basidia 4-spored, 20-26x 8-9, clavate, hyaline in KOH. Pleurocystidia
scattered, 38-50 x 10-13 x 8-10 t, narrowly utriform with subcapitate apex, some
Y-shaped, wall thin, smooth and hyaline, cell content not distinctive in KOH
or in Melzer's. Cheilocystidia 34-52 x 8-15 /, fusoid-ventricose with subacute
apex, fusoid-ventricose with short indistinct neck and broadly rounded apex,
elliptic-pedicellate (in optical section), or clavate, hyaline, smooth, thin-walled,
content not distinctive.
Gill trama regular, hyphae with inflated cells, walls smooth and hyaline.
Pileus cuticle a layer of vesiculose cells 2-3 deep, walls thin, smooth and
hyaline, numerous pileocystidia resembling the pleurocystidia or more variable
in shape present over some areas of the surface. Hyphae of the subcuticular
region with pale tawny incrustations and wall thickenings near the septa as
revived in KOH. Clamp connections present.
Type locality. Ophir, Colorado.
Habit and habitat. Gregarious under aspen.
Distribution. Colorado.
Observations. The Y-shaped cystidia are most peculiar but hardly diagnostic
on the basis of present information. They give one the impression of being
abnormal. The same applies to the pileocystidia. They are sporadic and may
occur only where insects have damaged the tissue. This impression needs further
verification. The reliable characters are the spore size, dark color of the spores
in KOH, narrowly utriform pleurocystidia and the cottony annulus which becomes
avellaneous in drying. This variant may eventually deserve recognition as an
autonomous species.
Material examined: Colorado: Smith 51837 (Type).
32. Psathyrella kauffmanii A. H. Smith, sp. nov.
Pileus (3-)4-8(-9) cm latus, campanulatus vel plano-umbonatus, interdum
late convexus, pallide spadiceus, ad marginem appendiculatus; sapor subamarus
vel mitis; lamellae angustae confertae adnatae, pallidae demum griseo-fuscae;
stipes 6-12 cm longus, (2.5-)3-10 mm crassus, albidus, deorsum interdum fibrillosus, sursum annulatus; annulus tenuis, striatus, saepe evanescens; sporae 7-9 x
4.5-5 /; pleurocystidia (34-)40-60 x10-18/, ad apicerum late rotundata vel
obtusa, saepe bifurcata; fibulae adsunt. Typus. Smith 66602 (MICH); legit prope
Big Bay, Michigan.