The North American species of Psathyrella.

1972]

PSATHYRELLA

247

Key to the Species of Section Cystidiosae
1. Wall of pleurocystidia frequently or regularly 2 u thick or more at least in the
neck near the apex. 2
1. Wall of pleurocystidia thinner (up to 1.5 u approximately). 4
2. Outer veil absent. 207. P. cystidiosa.
2. Outer veil present. 3
3. Spores 7-8.5 X 4-4.5 AL; outer veil thin and represented by a few patches of fibrils
near the margin of the pileus. 206. P. hesleri.
3. Spores 8-9.5(-10.5) X4-5(-5.5) u; outer veil copious and leaving fibrillose squamules
over entire pileus at first. 205. P. cloverae.
4. Pleurocystidia very sharply pointed; spores usually somewhat inequilateral
in profile. 208. P. stuntzii.
4. Not as above. 5
5. Spores 5-6.2 X 3.8-4.6 u; cespitose on rotten logs; Cuba. 217. P. euthugramma.
5. Spores 6 A or more long (see 76. P. paradoxa also). 6
6. Pleurocystidia with walls (in some at least) colored in KOH. 7
6. Pleurocystidia hyaline in KOH or soon becoming so. 8
7. Pleurocystidia with wall ~1.5 1u thick; pileus dark cinnamon brown at first.
214. P. olympiana.
7. Pleurocystidia with walls ~0.5 Iu thick; pileus ochraceous tawny young. 215. P. solitaria.
8. Pileus developing pinkish tints when faded; spores ovate to angular-ovate
in face view. 216. P. sharonensis.
8. Not as above. 9
9. Veil present either over the pileus or along the margin at first. 10
9. Veil absent or practically so. 11
10. Spores 8-11 X 5-6,u; pileus margin appendiculate. 204. P. sublongipes.
10. Spores 7.8-9.3 X 3.7-4.5 /u; pileus at first dotted with fibrillose flecks.
399. P. atomatoides.
11. Cheilocystidia voluminous (40-120 x 9-15,); spores 7-8X4-4.5x4.5-5.5 t.
213. P. crenulata.
11. Not as above. 12
12. Spores 7-9 X 3.5-4.5 A. 13
12. Spores 6-7.5 X 3.5-4.5,. 14
13. Spores revived in KOH soon pale chocolate gray in KOH. 212. P. cernua.
13. Spores becoming dark chocolate color in KOH. 211. P. polycephala
14. Pleurocystidia with walls up to 0.7, thick, the apex subacute to obtuse.
209. P. submaculata.
14. Pleurocystidia thin-walled, utriform to obtusely fusoid-ventricose.
210. P. saccarinophila.
204. Psathyrella sublongipes A. H. Smith, sp. nov.
Pileus 1-4 cm latus, convexus, glaber, spadiceus; lamellae confertae, angustae,
brunneolae, demum fusco-brunneae; stipes 5-9 cm longus, 2.5-4 mm crassus;
albidus, sursum pruinosus, glaber (velum nullum); sporae 8-11x 5-6,; pleurocystidia 40-70 x 10-18 g, late fusoideo-ventricosa, late rotundata vel obtusa;
fibulae adsunt. Typus. Smith 37181 (MICH); legit prope Riggins, Idaho.
Pileus 1-4 cm broad, convex, expanding to plane with a spreading margin,
surface glabrous, moist, hygrophanous, striatulate before fading, color dingy
yellow-brown (near "Dresden brown"), becoming paler (near "buckthorn brown")
before fading to pinkish buff, margin at first appendiculate with remnants of
the veil. Context very thin and fragile, odor not distinctive.
Lamellae close, narrow, adnate, seceding, pallid brownish but finally darkening to fuscous, edges pallid, crenulate under a lens (no pink present).
Stipe 5-9 cm long, 2.5-4 mm thick, equal, white to whitish, fragile, not
appreciably discoloring below, apex pruinose, glabrous or with a few appressed
fibrils lower down.
Spores 8-11 x 5-6 g, smooth, apical pore distinct and apex truncate, shape in