The North American species of Psathyrella.

1972]

PSATHYRELLA

215

truncate at apex, the color of the spores in Melzer's and thin, narrow, white,
immature gills make this a rather distinct species.
Material examined. UNITED STATES. Michigan: Smith 20997. New
York: (Peck's type). Tennessee: Hesler 17964. CANADA. Ontario: Smith
4507.
172. Psathyrella pellstonensis A. H. Smith, sp. nov.
Pileus 1-2 cm latus, anguste conicus demum campanulatus, candidus, sparse
fibrilloso-squamosus, glabrescens; lamellae confertae, angustae, candidae demum
violaceo-fuscae; stipes 4-6 cm longus, 2-3 mm crassus, candidus, deorsum fibrillosus, glabrescens; sporae 6-7 x 3.5-4 /; pleurocystidia 32-44x9-14 I, utriformia;
fibulae desunt. Typus. Smith 39186 (MICH); legit prope Pellston, Michigan.
Illust. P1. 58, fig. c; Text Figs. 389-392.
Pileus 1-2 cm broad, narrowly conic and expanding to narrowly campanulate,
snow-white over all and thinly covered by appressed scattered fascicles of white
veil fibrils, white beneath the veil, hygrophanous, fading to a dead white and the
disc finally cream color, glabrescent in age and dingy over marginal area as gills
become wood-brown. Context white and exceedingly fragile, odor and taste not
distinctive.
Lamellae close, ascending adnate, narrow, white, becoming "wood brown" to
"benzo brown" (violaceous-fuscous) and lacking a red component in the color,
edges even.
Stipe 4-6 cm long, 2-3 mm thick at apex, equal, very fragile, snow-white and
unchanging, with scattered white remains of the veil over lower half but these
variously dispersed and not forming an annular zone.
Spores 6-7 x 3.5-4 ui, smooth, germ pore scarcely evident, in HO dark cocoacolor, dark chocolate in KOH, subellipsoid.
Basidia 18-24x 6-7(-8) Iu, short-clavate, 4-spored, hyaline in KOH. Pleurocystidia 32-44x 9-14 It, utriform, thin-walled, hyaline in KOH, smooth, content
in no way distinctive in KOH or Melzer's. Cheilocystidia similar to pleurocystidia.
Caulocystidia abundant near the apex only, 32-54 x 9-15 /u, utriform and similar
to pleurocystidia or clavate to fusoid-ventricose, rarely with a lateral protuberance, content of cell hyaline in KOH, walls thin and smooth.
Pileus cuticle of vesiculose cells up to 30,/ wide, the layer 2-3 cells deep, their
walls thin, smooth and hyaline in KOH, occasional filamentous hyphae 3-4 p
diam. projecting as pileocystidia. Subcutis of hyaline inflated hyphae, numerous
laticiferous elements present which in Melzer's are bright yellow and have a
homogeneous content. No amyloid or other distinctive reaction present on any
tissue as revived in Melzer's. Clamp connections could not be found.
Type locality. Pellston, Michigan, in the hills west of town.
Habit and habitat. Scattered along an old logging road in beech-maple forest,
September.
Distribution. Michigan.
Observations. This species features an apparent lack of clamps on the hyphae
of the basidiocarp-a very unusual feature in the genus. The well-developed outer
veil is typical of the group. The lack of distinct pigmentation in the pileus and
the presence of utriform pleurocystidia along with the small spores amply
distinguish it as a species.
Material examined. Michigan: Smith 39186 (Type), 42130, 60920, 63558,
63630, 63706, 63711.