The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Stirps Hirtosquamulosa
This stirps features pale spores in KOH, fibrillose squamulose pilei, and lack
of pigmented content in the hyphae of the fibrils when these are mounted in
KOH. The color of the squamules noted on fresh material is apparently due to
pigment in the cell wall. The type of the subgenus, P. melanthina may also
belong in this stirps, but I have not studied it critically. As mentioned previously,
there is more than one concept of the latter in the literature.
10. Psathyrella hirtosquamulosa (Peck) A. H. Smith, comb. nov.
Agaricus hirtosquamulosus Peck, Bull. Buffalo Soc. Nat. Sci. 1: 53. 1873.
Hypholoma hirtosquamulosum (Pk.) Saccardo, Sylloge Fung. 5: 1037. 1887.
Hypholoma irregulare Parker, Mycologia 25: 174. 1933.
Illust. PI. 8, fig. a; Text Figs. 18-21.
Pileus 1-3.5 cm broad, obtuse to convex with the margin at first incurved,
becoming broadly convex to nearly plane, surface moist and hygrophanous
beneath a sparse to copious innate fibrillose covering which becomes broken up
into erect to somewhat decumbent fine dark-colored squamules especially around
the disc, the fibrils dark brown to blackish brown, surface beneath grayish buff,
avellaneous or dark drab (all when moist), fading to pallid, smooth to rugulose.
Context pallid to gray, thin and very fragile, odor and taste not distinctive.
Lamellae adnate but soon seceding, broad, close, thin, pallid at first but soon
drab and finally dark purplish brown, edges white-fimbriate.
Stipe 2-4 cm long, 1.5-2 mm thick, equal, fragile, ground color white or pallid
but this obscured by coarse appressed dark fibrils similar to those occurring on the
pileus, apex pruinose; veil submembranous and all traces along the margin soon
vanishing, not leaving a distinct ring on the stipe where it breaks.
Spores 6-7(-8)x 4-4.6x4.5-5.5(-6) a, smooth, apex rounded (but pore not
distinct), shape in face view corn-kernel-shaped, some with a slight medial constriction, some very broadly ovate, typically truncated at the apiculate end, in
profile view somewhat bean-shaped to obscurely pistol-like because of a slight
bulge at the apiculus, color revived in KOH pale for the genus and a dingy
ochraceous-olive after standing for a few minutes, in Melzer's pale reddish
cinnamon, wall about 0.3 p thick.
Basidia 15-18(-22) X 6-8.5 a, 4-spored, hyaline in KOH, clavate, many with
refractive particles in them as revived in KOH, not distinctive in Melzer's.
Pleurocystidia 30-45x 10-18 a, very broadly utriform and as revived in KOH
typically with a cap of incrusting olive to dingy ochraceous amorphous material,
walls thin and hyaline, content not distinctive in KOH or Melzer's. Cheilocystidia
similar to pleurocystidia or more saccate-pedicellate. Caulocystidia numerous
near apex, 40-80 x 10-25 Iu, subvesiculose to elongate-clavate, smooth, thin-walled,
content not distinctive, hyaline to weakly yellowish in KOH.
Cuticle of pileus of inflated cells 2-4 deep, the walls thin and smooth and in
KOH hyaline to weakly ochraceous; the hairs of the pileus of hyphae 10-25 /u
wide, cells with smooth pale brownish (in groups in KOH) walls, no tendency for
the cells to disarticulate noted and no pigmented content evident in either KOH
or Melzer's. Context hyphae hyaline in KOH and weakly yellowish in Melzer's.
Clamp connections present. No amyloid reaction present on any tissue or in
any cells.
Type locality. Portville, New York.
Habit and habitat. Solitary to scattered or gregarious on logs and debris of