The North American species of Psathyrella.

1972]

PSATHYRELLA

179

Basidia 4-spored, 18-25 x 5-8 aL, hyaline, clavate. Pleurocystidia 40-55 (-66) x
10-15 /A, fusoid-ventricose with obtuse apex, smooth, hyaline in KOH, thin-walled
cell content not distinctive in either KOH or in Melzer's. Cheilocystidia similar
to pleurocystidia or vesiculose and 10-15, wide. Caulocystidia versiform:
(1) subfilamentose (rare) and up to 60x 8 /; (2) fusoid-ventricose and resembling
pleurocystidia (rather common), 38-60x 10-18 /I; (3) clavate in various degrees
and up to 18 /u wide (fairly common).
Gill trama regular, when first revived in KOH having a strong vinaceousbrown cast but soon fading to hyaline or merely sordid brownish, pigment in the
walls. Pileus having a cuticle consisting of a layer of vesiculose cells usually
several deep and having yellowish walls as revived in KOH, the walls of the basal
cells and hyphae next to them distinctly rusty brown in KOH thus forming more
or less of a demarcation line between the cuticle and the context. Hyphae of
the context strongly vinaceous-brown when first revived in KOH but soon dull
cocoa-color (or retaining a vinaceous tint). Clamp connections present. No
distinctive reactions noted on any tissue mounted in Melzer's.
Type locality. Greenbrier, Great Smoky Mountains National Park, Tennessee.
Habit and habitat. In loose clusters on soil.
Distribution. Known only from the type locality.
Observations. This species is clearly a close relative of P. microsperma but
is distinguished in the fresh condition by the much longer and more numerous
pleurocystidia and the olive-brown gills. The points of similarity are the very
inconspicuous apical germ pore of the spores, the more or less cespitose habit, thin
veil and reaction of the context in KOH, but in P. subfasciculata the cells of the
cuticle have yellow to rusty yellow to brown walls as revived in KOH in contrast
to the hyaline cells in P. microsperma.
136. Psathyrella idahoensis A. H. Smith, sp. nov.
Pileus 2-4 cm latus, late conicus vel convexus, ad marginem denticulatoappendiculatus, glaber, fulvus; lamellae subdistantes, latae, adnatae, brunneolae
demum griseo-brunneae; stipes 3-6 cm longus, 2.5-5 mm crassus, deorsum brunneus, sparse fibrillosus, glabrescens; sporae 7-8.5x4-4.5 I,; pleurocystidia 42 -64x9-16 IA, fusoide ventricosa, subacuta; fibulae adsunt. Typus. Smith 70159
(MICH); legit prope, Warren, Idaho.
Illust. Text Figs. 307-310.
Pileus 2-4 cm broad, obtusely conic, expanding to broadly conic or nearly
convex, margin straight and at first denticulate-appendiculate with fragments of
the white submembranous veil, surface glabrous, moist, hygrophanous, tawny
("tawny") when fresh, fading to near "cinnamon-buff" (pale tan). Context
exceedingly thin and fragile, odor and taste not distinctive, with FeSO, no color
change.
Lamellae broad, subdistant, adnate then seceding, pallid brownish becoming
hair brown.
Stipe 3-6 cm long, 2.5-5 mm thick, equal, hollow, fragile, white and thinly
fibrillose, in age becoming dingy brownish beneath the fibrils, finally glabrous.
Spores 7-8.5 x 4-4.5 pa, smooth, apical pore present but obscure, shape in face
view ovate to elliptic, in profile obscurely inequilateral to subelliptic, color in
KOH cocoa-color darkening to dark smoky chocolate-brown, in Melzer's reddish
tawny, wall about 0.2 pu thick.
Basidia 4-spored, 18-24x8-10 /A, hyaline in KOH, clavate. Pleurocystidia