The North American species of Psathyrella.

CIAro e

-1 n P-n

1/2]J PSATHYRELLA 2Uo
area, finally entirely glabrous, hygrophanous and fading to a dingy tan. Context
very thin and delicate, concolorous with surface, no odor or taste evident.
Lamellae close, broad, adnate, seceding, dingy cinnamon-brown before becoming gray-brown ("hair brown") from the spores.
Stipe 3-5 cm long, 1-1.5 mm thick, equal, hollow, delicate and fragile, with
scattered fibrils over lower portion but soon glabrescent, dingy brown over all
except the pallid apical region, pruinose above.
Spores 9-12 x 5-6 i, smooth, apical pore distinct, in face view elliptic to oblong,
in profile as seen in optical section the ventral line nearly straight and the dorsal
line convex (very obscurely inequilateral), color in KOH a medium fuscous, in
Melzer's bay-red, wall about 0.4 K thick.
Basidia 4-spored, 18-24x9-12 I, clavate, hyaline in KOH. Pleurocystidia
37-54x8-14 /i, fusoid-ventricose with short or long flexuous neck ending in an
acute to subacute apex, smooth, thin-walled, hyaline in KOH, content not distinctive in KOH or in Melzer's. Cheilocystidia fusoid-ventricose and like the
pleurocystidia but varying to vesiculose or neck very short. Caulocystidia similar
to pleurocystidia but up to 70x 18 ft occasionally, also numerous vesiculose cells
present in patches of the caulocystidia.
Pileus with a cuticle of a layer of inflated cells 1-2 deep, the cells with hyaline,
smooth, thin walls and lacking a distinctive content in either KOH or in Melzer's.
Trama of pileus including the subcutis of brown-walled hyphae as revived in
KOH but the color fading and the cell walls smooth. Clamps present. No
distinctive reactions observed on any tissue in Melzer's.
Type locality. Burgdorf, Idaho County, Idaho.
Habit and habitat. Gregarious on wet moss under willow and dwarf birch,
August.
Distribution. Known only from the type locality.
Observations. The medium-large spores, acute pleurocystidia of the P. gracilis type, lack of brachybasidioles in the hymenium, very delicate brown stipe,
striate pileus when moist, and lack of any change to pink on the gill edges
distinguish this species.
162. Psathyrella rubescens A. H. Smith, sp. nov.
Pileus 10-15 (-20) mm latus, obtuse conicus demum campanulatus, albofloccosus, glabrescens, spadiceus, dein ad marginem incarnatus; lamellae latae,
confertae, avellaneae demum griseo-fuscae; stipes 3-5 cm longus, 1-1.5 mm crassus, deorsum sordide brunneus, fibrillosus, glabrescens; sporae 10-13(-14) x 5.5 -6.5(20x 12) t; pleurocystidia 30-42x 10-15 pt, late fusoide ventricosa, obtusa vel
subacuta; fibulae adsunt. Typus. Smith 29352 (MICH); legit prope lower
Tahoma Creek, Mt. Rainier National Park, Washington.
Pileus 10-15 (-20) mm broad, obtusely conic, becoming campanulate to
expanded-umbonate, surface of buttons decorated over all with fine white superficial flecks of the outer-veil fibrils, soon becoming entirely glabrous, when young
the disc "Prout's brown" and the remainder "cinnamon-brown" beneath the white
veil, with a pink tinge pervading the marginal area at least before changing color
from fading, fading to cinnamon-buff or pale pinkish buff on the disc first, margin
fading to near "vinaceous-buff." Context thin and fragile, concolorous with
surface either moist or faded, finally pallid, odor and taste not distinctive.
Lamellae only moderately close, broad, ascending to bluntly adnate, "avellaneous" to near wood brown, becoming "hair brown" at maturity (with a strong
gray cast), edges even.