The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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truly truncate, shape in face view oblong to narrowly ovate, in profile obscurely
inequilateral to subelliptic, color in KOH date brown slowly becoming dark
chocolate-color, in Melzer's dark reddish tawny, wall about 1,u thick.
Basidia 22-30 x 10-13 fu, clavate, 4-spored, hyaline in KOH. Brachybasidioles
present by late maturity. Pleurocystidia 40-60 x 9-16 J, fusoid-ventricose, tapered
to a subacute apex or apex spathulate or branched, wall thin, smooth and hyaline,
cell content not distinctive. Cheilocystidia similar to pleurocystidia varying to
shorter, some clavate cells also present. Caulocystidia versiform: fusoidventricose, subcylindric or clavate, smaller than the pleurocystidia, apex acute
to rounded or at or near apex some branching.
Gill trama regular, hyaline to pale brownish in KOH. Pileus trama regular,
hyaline to pale brownish in KOH, ochraceous pigment deposits near the cross walls
in many subcuticular hypae. Pileus cuticle of vesiculose and pear-shaped cells
intermingled and one cell deep, hyaline, not arranged in a distinct palisade.
Clamps present.
Type locality. Dexter, Michigan.
Habit and habitat. Scattered on wet leaves.
Distribution. Michigan.
Observations. No change to pink was observed in this species, and many of
the pleurocystidia are branched near the apex or show subapical protrusions. It
appears to be very close to P. corrugis.
Material examined. Michigan: Smith 4991 (Type), 11042.
311. Psathyrella brachycystis A. H. Smith, sp. nov.
Pileus 7-12 mm latus, campanulatus, ad marginem sparse floccosus, glabrescens, in exsiccati griseo-alutaceus; lamellae latae, subdistantes fusco-brunneae;
stipes 2-3 cm longus, circa 1 mm crassus, in exsiccatio brunneus; deorsum
fibrilloso-floccosus; sporae 11-15 x 6.5-8 /; pleurocystidia 34-42x12-19 u, late
fusoideo-ventricosa, ad apicerum acuta; cutis pileum hymeniformis; fibulae
adsunt. Typus. Brooks 1605 (MICH); legit prope Edwards, Kansas.
Illust. Text Figs. 669-672.
Pileus 7-12 mm broad, broadly campanulate to nearly convex in buttons,
becoming more broadly campanulate to nearly hemispheric at maturity, veil not
conspicuous and adhering as small patches of white fibrils on or near the margin,
glabrescent, color when fresh not noted, when dried grayish over margin and disc
tinged with ochraceous-buff. Context very thin and delicate.
Lamellae broadly adnate to slightly arcuate as seen in dried material, broad,
subdistant, pallid brownish in dried buttons, chocolate-brown with white fimbriate
edges in mature dry pilei.
Stipe short, 2-3 cm long, about 1 mm or less thick, equal, dull brown when
dried (consequently very likely discoloring when fresh), with scattered white
fibrillose flecks of veil fibrils over lower part, base white mycelioid where attached
to the mud.
Spores 11-15 x 6.5-8 u, smooth, truncate from a wide apical pore, shape in face
view ovate to elliptic, in profile obscurely inequilateral to subovate, color in KOH
bister soon becoming dark chocolate-color, in Melzer's reddish tawny to bay, wall
about 1 /A thick.
Basidia 4-spored, 26-32 x 10-13,/, subcapitate, hyaline in KOH. Pleurocystidia scattered, broadly fusoid-ventricose, 34-42 x 12-19 /u, neck short and apex
acute, wall thin, smooth and hyaline, cell content not distinctive. Cheilocystidia