The North American species of Psathyrella.

1972]

PSATHYRELLA

291

Section Umbonatae A. H. Smith, sect. nov.
Pleurocystidiis utriformibus vel late obtusis; sporae 9-12 / vel maior longae.
Typus. Psathyrella umbonata.
Key to the Species of Section Umbonatae
1. Spores 12-17 / long. 2
1. Spores 9-12.5 /u long. 9
2. Stipe tinged vinaceous at first; pleurocystidia voluminous. 3
2. Not as above. 4
3. Pileus trama as revived in KOH with a fuscous to gray-brown tone; odor not
distinctive. 62. P. barlae.
3. Hyphae of pilear trama vinaceous-brown in KOH; odor when fresh metallicdisagreeable. 257. P. pseudocorrugata.
4. Spores 7-9(-10) u wide. 5
4. Spores 6-8 u wide. 6
5. Taste farinaceous; growing in clusters. 258. P. caespitosa.
5. Taste not known; growing on sandy soil gregariously. 259. P. rooseveltiana.
6. Apex of pleurocystidia (as revived in KOH) filled with highly refractive
granules; pileus rosy isabelline (Murrill). 260. P. orizabensis.
6. Not as above. 7
7. Growing on conifer duff. 261. P. pseudofrustulenta.
7. Gregarious on chip-dirt from hardwoods, or on soil. 8
8. Faded pileus margin flushed pink in some basidiocarps; veil absent.
262. P. pseudofoenisecii.
8. Not as above, with a thin grayish veil at first. 263. P. umbonata.
9. Stipe 6-12 mm thick. 264. P. pseudolarga.
9. Stipe narrower. 10
10. Spore apex not truncate (apical pore very narrow under oil). 11
10. Spore apex truncate or pore forming a lens-shaped cap. 15
11. Basidiocarp small and Galerina-like; stipe less than 1 mm thick. 265. P. galerinoides.
11. Stipe thicker than in above choice. 12
12. Pileus gray to grayish when young; spores clay color immediately upon
being revived in KOH. 266. P. infilatocystis.
12. Not as above. 13
13. Stipe 5-10 cm long, 2-3.5 mm thick; veil absent. 267. P. baileyi.
13. Stipe 3-5 cm long, 2-4 mm thick; veil present or if absent and basidiocarps on
pine chips see next choice. 14
14. Gregarious on chips of pine; spores 9-12 X 5-7.5,. 268. P. pinicola.
14. Clustered on wood of aspen; spores 9-11 X 5-6 /. 269. P. parvivelosa.
15. Spores rather distinctly inequilateral in profile. 270. P. prunuliJormis.
15. Not as above. 16
16. On burned areas; hyphae of pileus context heavily incrusted; pileus shining
when moist (as in lubricous pilei). 271. P. laeta.
16. Not as above. 17
17. Pleurocystidia 48-72 X 8-12 ~. 272. P. ramicola.
17. Pleurocystidia shorter than in above choice. 18
18. Cuticle of pileus about one cell deep. 273. P. subpalustris.
18. Cuticle of pileus 3-5 cells deep. 274. P. lithocarpi.

257. Psathyrella pseudocorrugata A. H. Smith, sp. nov.
Pileus 1-3.5 cm latus, conicus, glaber, hepaticolor, demum rugulosus; contextu
in "KOH" griseus; lamellae "vinaceous buff" demum vinaceo-brunneae dein fuscobrunneae, latae, demum subdistantes; stipes 3-7 cm longus, 2-3.5 mm crassus,
vinaceo-tinctus demum pallidus deorsum sparse fibrillosus; velum sparsum;
sporae 14-16 x 5.5-7.5 [; pleurocystidia 46-80 x 12-25 I versiformia; fibulae adsunt. Typus Smith. 64875 (MICH); legit prope Ann Arbor, Michigan.