The North American species of Psathyrella.

1972]

PSATHYRELLA

399

the pileus cuticle, the slender stipe which darkens over the lower portion, and
a habitat on sphagnum moss. It is close to P. obtusata in aspect.
Material examined. Idaho: Smith 66306. Michigan: Smith 43743 (Type),
51068.
375. Psathyrella paludosa A. H. Smith, sp. nov.
Pileus 2-3 cm latus, convexus vel campanulatus, glaber, castaneus, demum
rugulosus; sapor subamarus; lamellae latae, confertae, subochraceae demum spadiceae; stipes 3-5 cm longus, 3-5 mm crassus, melleibrunneus, deorsum fuscescens,
sparse fibrillosus; sporae 6.5-8x4-4.5 /u; pleurocystidia 27-64x9-15 pu, fusoide
ventricosa, obtusa vel acuta; fibulae adsunt. Typus. Smith 50734 (MICH); legit
prope Tahquamenon Falls, Luce County, Michigan.
Illust. Text Figs. 762-765.
Pileus 2-3 cm broad, obtuse when young, expanding to campanulate or convex, surface glabrous or with a few appressed fibrils near the margin, margin
fringed at first with grayish remnants of a partial veil, color chestnut-brown when
moist, becoming russet, surface slightly wrinkled. Context thin, fragile, concolorous, odor none, taste slightly disagreeable.
Lamellae broad, close, depressed-adnate, 1-2 tiers of lamellulae, dingy buff
when young, becoming nearly date brown ("Saccardo's umber") at maturity, edges
even.
Stipe 3-5 cm long, 3-5 mm thick, equal, fragile, ground color dingy honey
brown, darkening more at the base, pallid brown from a thin fibrillose to scurfy
coating of veil remnants, apex pallid and striate from gill impressions.
Spores 6.5-8x4-4.5 p, smooth, with an inconspicuous apical pore (apex not
truncate), shape in face view ovate to elliptic, in profile obscurely bean-shaped
to subelliptic, color in KOH dark chocolate-color, in Melzer's dull reddish tawny,
wall about 0.2 p thick.
Basidia 18-22x5-7,u, short-clavate, hyaline in KOH. Pleurocystidia scattered, 37-64x 9-15 /A, fusoid to fusoid-ventricose, apex acute to obtuse, wall thin
and hyaline, with a slight amorphous incrustation near the apex when first revived
in KOH, content "empty." Caulocystidia present on loose fibrils over stipe surface, versiform (Fig. 765), smooth, thin-walled, hyaline. Hyphae of the stipe dull
vinaceous-cinnamon in KOH but fading (sections brown to the naked eye), with
a very fine roughness over the walls of the hyphae of the cortex.
Pileus with a cuticle of a layer of vesiculose cells 2-3 deep and hyaline in
KOH, subcuticular layer vinaceous-cinnamon in KOH but fading, tramal hyphae
also vinaceous-cinnamon in KOH and fading, walls smooth. Clamps present. No
tissue giving a distinctive reaction in Melzer's.
Type locality. Tahquamenon Falls State Park, Luce County, Michigan.
Habit and habitat. Gregarious on a patch of dead Sphagnum (probably killed
by the fungus), October.
Distribution. Michigan.
Observations. This species is, possibly, parasitic on the Sphagnum in the
manner of Lyophyllum palustre. It is distinguished by a somewhat disagreeable
taste, highly colored pileus gill and stipe tissue as revived in KOH, a dingy honeycolored stipe when fresh, small spores and prominent pleurocystidia.
376. Psathyrella katmaiensis. Wells, Kempton & A. H. Smith, sp. nov.
Pileus 9-15(-35) mm latus, campanulatus, ad marginem tenuiter fibrillosus,
glaber, castaneus; contextu castaneus; lamellae pallidae, demum atro-brunneae;