The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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Stipe 3-5 cm long, 1-1.5 mm thick, equal, hollow, fragile, whitish, becoming
dingy or even dull brownish near base, lower part at first with veil fibrils variously
dispersed, glabrescent, apex pruinose.
Spores 10-13 (-14) x 5.5-6.5 It (occasional giant spores 20 x 12 /u approximately
also present), smooth, apical pore broad and apex truncate, shape in face view
more pointed at the apiculate end than at the apex (where in dark colored spores
the pore as such does not show clearly), basically elliptic, in profile somewhat
inequilateral to obscurely inequilateral, color in KOH blackish brown but many
paler spores present, in Melzer's dark tawny-red, wall 0.6-1.5 IL thick.
Basidia 2- and 4-spored 20-25x 10-14 IL, hyaline in KOH, subglobosepedicellate. Brachybasidioles present. Pleurocystidia scattered to abundant,
30-42x 10-15 i, broadly fusoid-ventricose with short neck and obtuse to subacute apex, hyaline in KOH, smooth, thin-walled. Cheilocystidia of three types:
the first rare and resembling the pleurocystidia, the second rare and inconspicuous, subcylindric to subfusoid, 12-15 x 4-6 i, and some of these with a refractive
thickening in the apex, the third type clavate-vesiculose 10-16 x 7-12 i/, the basal
hyphae slightly yellowish in KOH on some. Caulocystidia resembling all of the
different types of cheilocystidia.
Gill trama vinaceous-brown fading to cocoa-brown and in old pilei fading to
near hyaline. Pileus trama cocoa-vinaceous in young material mounted in KOH,
paler to near hyaline on old pilei. Cuticle of pileus a layer of vesiculosepedicellate cells one cell deep, the walls thin, smooth and hyaline, the content
of the cells not distinctive. Clamp connections present.
Type locality. Lower Tahoma Creek, Mt. Rainier National Park, Washington.
Habit and habitat. Gregarious on rich humus under alder.
Distribution. Washington.
Observations. The distinct outer veil, the tendency for the pileus to become
pink over the marginal area, the generally delicate stature, large spores, characteristic pleurocystidia, and KOH reactions of the tramal hyphae in pileus and
hymenophore distinguish it. It is close to P. trepida but has a distinct veil.
Material examined. Washington: Smith 29352 (Type), 29353, 29354, 29355,
29596,29766.
163. Psathyrella substrigosipes A. H. Smith, sp. nov.
Pileus 10-15 mm latus, late conicus vel convexus, fibrilloso-floccosus, glabrescens, cinnamomeo-brunneus; lamellae confertae, latae, brunneolae demum
purpureo-brunneae; stipes 3-5 cm longus, 1-1.5 mm crassus, brunneus sed
deorsum sordide brunneus; sporae 11-14x 5.5-6.5 Iu; pleurocystidia 48-64x 10 -18 IL; fusoideo-ventricosa, ad apicerum late rotundata vel obtusa; fibulae adsunt.
Typus. Smith 75678 (MICH); legit prope Burt Lake, Michigan.
Illust. P1. 88, fig. b.
Pileus 10-15 mm broad, obtuse when young, expanding to broadly conic or
convex, with or without a slight umbo, margin with scattered squamules of veil
fibrils but these soon vanishing and pileus glabrous and shining, cinnamon-brown
fading to pale tan and scarcely atomate when faded. Context dark colored, very
thin, odor not distinctive.
Lamellae close, broad when mature, ascending and adnate with a decurrent
tooth (hooked), seceding, brownish pallid at first, becoming cocoa-brown and then
darker from the spores, edges crenulate and pallid.