The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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387. Psathyrella pseudovernalis A. H. Smith, sp. nov.
Pileus 2-3.5 (-5) cm latus, campanulatus vel late convexus, ad marginem
leviter fibrillosus; glabrescens, sordide melleibrunneus, demum fusco-brunneus,
lamellae confertae, latae (5-6 mm), pallidae demum sordide vinaceo-brunneae,
ad acierum demum incarnatae; stipes (3-)4-8(-10) cm longus, (1.5-) 2-3 (-5) mm
crassus, dissiliens, albidus vel pallidus; glaber; velum sparsum; sporae 7-8.5
(-9) x4-5,u; pleurocystidia 38-60(-70) x10-15 u, fusoide ventricosa, obtusa;
fibulae adsunt. Typus. Smith 14037 (MICH); legit prope Lake Crescent, Washington (Olympic National Park).
Illust. P1. 93, fig. b; Text Fig. 799-801.
Pileus 2-3.5(-5) cm broad, convex to obtusely conic when young, becoming
broadly campanulate to convex or nearly plane, sometimes with a slight umbo,
surface at first covered with faint white fibrils along or near the margin, soon
glabrous, smooth or slightly rugulose, "ochraceous-tawny" to "buckthorn brown"
(dull honey brown) but becoming grayish and then "wood brown" (dark avellaneous), in age however dark reddish brown ("Mars brown") when wet, hygrophanous, fading to pale dingy tan. Context concolorous with surface, very thin
and fragile, odor and taste not distinctive.
Lamellae close, 28-33 reach the stipe, broad, (5-6 mm), bluntly adnate, soon
seceding, pallid ("tilleul buff") young, soon fawn-color and finally "Natal brown"
(vinaceous-brown), very fragile, edges concolorous at first, often pinkish in age.
Stipe (3-)4-8(-10) cm long, (1.5-)2-3(-5) mm thick, equal or slightly tapered
upward, hollow, very fragile, readily splitting longitudinally when broken, white
to whitish, at first with faint white fibrillose flecks from the thin to rudimentary
veil, soon glabrous, base sparsely strigose.
Spores 7-8.5(-9) x4-5 /L, smooth, apical pore distinct but small and apex not
distinctively truncate, shape in face view elliptic to ovate, in profile subelliptic
to very obscurely inequilateral, color in KOH dark cocoa-color slowly becoming
a medium chocolate color, in Melzer's reddish tan to pale bay, wall about 0.5 /
thick (in KOH).
Basidia 4-spored, 17-22x7-10 /A, short-clavate, hyaline in KOH. Pleurocystidia abundant, 38-60 (-70) x 10-15,u, fusoid-ventricose, apex obtuse, wall thin,
smooth and hyaline, cell content not distinctive in KOH or Melzer's. Cheilocystidia similar to pleurocystidia varying to broadly and bluntly fusoid to nearly
clavate and 28-37x9-15 /,, also present are subcylindric to clavate cells 10-24x
5-12,u with yellowish slightly thickened walls as revived in KOH. Caulocystidia
present only as a few recurved hyphal ends clavate to more or less subfusoid.
Gill trama of interwoven hyphae with inflated cells dingy vinaceous-brown in
KOH but gradually fading particularly in old pilei. Pileus trama colored as for
the gill trama or darker but also fading, hyphae of the subcuticular region with
fine incrustations or pigment deposits. Cuticle of the pileus a layer of hyaline
inflated to clavate cells one or two cells deep, the walls thin, hyaline to yellowish
or (when young) cinnamon. Clamps present.
Type locality. Lake Crescent, Washington.
Habit and habitat. Solitary to gregarious on humus and debris under alder
and cottonwood, particularly close to logs, stumps etc., vernal.
Distribution. Michigan, Washington.
Observations. P. vernalis, a European species, apparently has paler spores.
Material examined. Michigan: Hoseney 1581; Smith 33725, 33726, 33739,
33759, 33810, 50682. Washington: Smith 14037 (Type).