The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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smooth, thin-walled, hyaline. Cheilocystidia more or less similar to pleurocystidia,
hyaline in KOH.
Cuticle of pileus a layer of vesiculose cells 1-2 deep, the walls thin but slightly
refractive, smooth, hyaline to ochraceous in KOH. Hyphae of subcuticular zone
pale to rich rusty brown in KOH (paler on standing), walls roughened when
highly pigmented. Clamps present.
Type locality. Ithaca, Michigan.
Habit and habitat. Cespitose on rotten wood inside a hollow soft-maple tree,
October.
Distribution. Known only from the type locality.
Observations. This species appears to be related to P. emmetensis but differs
in the features of the pleurocystidia and in the rapidity with which the spores fade
to pale chocolate-gray with a slight ochraceous tint when mounted in KOH. There
was no rooting base or any evidence of even a rudimentary oozonium.
156. Psathyrella squamifera Karsten, Symb. Mycol. Fennicam (Medd. Soc.
Fauna Flora Fenn. 9: 1882) X: 60. 1882 (spelled Psatyrella in error).
Pileus 10-25 mm broad, obtusely conic at first and the margin appressed
against the stipe, becoming broadly conic or finally nearly plane, surface at first
covered with superficial easily removed white fibrils, the fibrils becoming
appressed into fascicles or scales and finally the pileus glabrous, color "chocolatebrown" to "warm sepia" (deep reddish brown), hygrophanous and fading to
"pinkish buff" or "cinnamon-buff" (very pale alutaceous), not conspicuously
striate when moist. Context very thin and fragile, odor none, taste not recorded.
Lamellae narrow, close, adnate, cinnamon-buff then blackish brown, margin
white-fimbriate.
Stipe 8-12 cm long, 1.5-2.5 mm thick, equal, strict, hollow, very fragile, surface
whitish from a fibrillose covering or the fibrils loosely arranged in fascicles, somewhat glabrescent, more or less fibrillose-pruinose near the apex.
Spores 10-13 x 4.5-6.6 a, smooth, apical pore distinct and apex somewhat
truncate if hyaline apical lens-shaped cap has collapsed, shape in face view
elliptic to slightly ovate, in profile subelliptic to obscurely inequilateral, color
in KOH chocolate-brown, in Melzer's reddish tawny, wall about 0.5 )l thick.
Basidia 4-spored, 26-30x 10-14 /, pedicel long and slender, hyaline. Pleurocystidia abundant 44-56(-60) x 10-16 A, fusoid-ventricose with narrow (4-6 p)
neck and obtuse to subacute apex, wall thin, smooth and hyaline, cell content not
distinctive in KOH or Melzer's. Cheilocystidia similar to pleurocystidia but
usually smaller. Caulocystidia in patches, roughly resembling the pleuro- and
cheilocystidia.
Gill trama regular, of large irregular cells more or less loosely interwoven,
dark rusty brown in KOH (not cocoa-colored). Pileus having a cuticle formed
by a palisade of ellipsoid to clavate cells with broad bases, their walls faintly
yellow to cinnamon (near base) in KOH. Hyphae of the pileus trama dark rusty
brown in KOH and the hyphae conspicuously incrusted with pigment patches and
bands. Clamp connections present.
Type locality. Finland.
Habit and habitat. Scattered on debris and mulch under alder and Thuja
mixed.
Distribution. Michigan.
Observations. This is a long-stiped species with smaller spores than P. gracilis
and with a well developed veil. Van Waveren (1971) discusses this species in