The North American species of Psathyrella.

1972]

PSATHYRELLA

347

Key to the Subsections of Section Fatuae
1. Habitat lignicolous. subsect. Lauricolae.
1. Habitat terrestrial or merely with basidiocarps attached to bits of woody debris.
subsect. Fatuae,
Subsect. Fatuae
Note: Psathyrella subagraria, P. parvifibrillosa, P. heterocystis, P. subnuda
and P. lubrica may key out here also.
Key to the Species of the Subsection Fatuae
1. Spores compressed (wider in face than in profile view). 2
1. Spores essentially terete. 4
2. On waste soil among weeds in Kansas. 319. P. ovatispora.
2. On duff under conifers. 3
3. Brachybasidioles present; lamellae blackish as dried; stipe 7-11 cm long, 3-6 mm
thick. 321. P. vesiculocystis.
3. Brachybasidioles absent; lamellae dark vinaceous brown as dried; stipe
3-5 cm X 1-2 mm. 320. P. abieticola.
4. Pinkish stains or flushes present on faded pilei or on gill edges and with
spores lacking a distinct apical truncation. 5
4. Not with the above features. 6
5. Spores 6.5-8 X 3.5-4.5 A. 322. P. georgiana.
5. Spores 8-10(-12) X 4.5-5.2 A. 323. P. vinescens.
6. Spores 7-9 X 3.3-3.8 A. 324. P. praecox.
6. Spores 4-5.5(-6) u wide. 7
7. Lamellae distant. 325. P. distantifolia.
7. Lamellae close varying to subdistant. 8
8. Stipe (4-)5-10 cm long, 2.5-6 mm thick. 9
8. Stipe shorter and more slender. 11
9. Taste bitter; lamellae close and narrow. 326. P. amarella.
9. Taste mild; lamellae broad to moderately broad. 10
10. Spores very soon fuscous revived in KOH; stipe white over all. 328. P. fusca.
10. Spores cocoa-color in KOH at first; stipe whitish above dingy tan below
when mature (but see 32a. P. kauffmanii var. exannulata and
P. lilaceogrisea also) 327. P. spadiceogrisea.
11. Spores not truncate at apex. 12
11. Spores truncate. 13
12. Stipe distinctly darkening near base by maturity; pileus when young
cinnamon-brown; in open pastures. 329. P. mazzeri.
12. Stipe hardly darkening; pileus when young pale honey brown; growing on
moist sand in shaded places. 330. P. psammophila.
13. Spores containing a medium-sized globule; brachybasidioles present at maturity;
on black muck in a swamp. 331. P. ephemera.
13. Spores lacking a globule; brachybasidioles not present; on well-drained humus
under alder; spores broadly elliptic in face view (but see 376. P. katmaiensis
and P. praetenuis also). 332. P. elliptispora.
319. Psathyrella ovatispora A. H. Smith, sp. nov.
Pileus 8-20 mm latus, late convexus, glaber, cinnamomeo-brunneus; lamellae
angustae demum sublatae, confertae demum subdistantes, fusco-brunneae; stipes
2-3 cm longus, circa 1 mm crassus, pallidus, deorsum demum brunneolus, sursum
pruinosus; sporae 7.5-8.8 x 5-5.5 x 5.5-6.3 u; pleurocystidia 36-44 x 10-12.5 ~,
subcylindrica, ad apicerum late rotundata; fibulae adsunt. Typus. Brooks 1616
(MICH); legit Geary County, Kansas.