The North American Species of Pholiota

51. Pholiota atripes sp. nov.

Illustrations: Text figs. 151-152.

Pileus 1-3 cm latus, planus, lucide flavo-brunneus, nitidus, glaber. Lamellae adnatae, flavo-albae deinde flavo-brunneae, confertae vel stipatae, marginibus pallido-serrulatae. Stipes 3-5 cm longus, 2-4 mm crassus, apice flavo-brunneus, albi obscuro-brunneus. Sporae 5-7.5 x 3.5-4 µ, ellipsoideae vel subovoideae, truncatae, pariete crassae, leves. Pleurocystidia desunt; cheilocystidia 30-50 x 7-10 µ, clavata vel subfusoidea. Cuticula gelatinosa. Caulocystidia desunt. Specimen typicum in Herb. Univ. Mich.; lectum prope Ledgewood, Wyoming, 28 Juni, 1959, L. E. Wehmeyer.

Pileus 1-3 cm broad, broadly convex with a decurved margin expanding to plane or with the disc slightly depressed, surface glabrous, viscid, light yellow-brown (collected in faded condition). Context thin, pliant, odor and taste not recorded.

Lamellae adnate, yellowish white, becoming pale to dark clay color when mature, crowded, narrow, bluntly adnate to slightly adnexed, edges serrulate and whitish.

Stipe 3-5 cm long, 2-4 mm thick, fibrous, apex light yellow-brown, the remainder dark brown to blackish brown, very dark in KOH, base white-mycelioid. Veil thin, fibrillose, leaving an apical evanescent fibrillose zone, with scattered fibrils lower down on the stipe.

Spores 5-7 (7.5) x 3.5-4 µ, smooth, in face view elliptic to ovate, in profile obscurely inequilateral, terete, wall thickened to about 0.3 µ, apical pore distinct and apex slightly truncate, in KOH pale tawny, slightly darker tawny in Melzer's reagent. Basidia 18-22 x 5-6.5 µ, 4-spored, clavate, hyaline in KOH, yellowish in Melzer's reagent. Pleurocystidia none. Cheilocystidia 30-50 x 7-10 µ, clavate to obtusely fusoid-ventricose, thin-walled, smooth, or with 1-2 apical projections in some. Caulocystidia scattered, clavate, similar to cheilocystidia in size or longer, pedicels in some yellowish in KOH.

Gill trama regular, hyphae somewhat interwoven; the subhymenium thin and not distinctive, hyphae of central area with cells 4-12 (15) µ wide, the walls as revived in KOH and Melzer's reagent thickened to 1-1.2 µ and with the middle lamella readily visible (1.3 N.A. objective), walls smooth and ochraceous to brownish in KOH, orange-ochraceous in Melzer's reagent. Pileus cutis a thin layer of gelatinous hyphae 2-4 µ diam., tubular, hyaline in KOH, walls finally asperulate; hypodermial region of interwoven thin-walled hyphae cells 6-15 µ diam. and dingy ochraceous in KOH, this layer occupying about half the pileus trama, the other half of hyphae with thickened walls like those of the gill trama and colored ochraceous to brownish in KOH, more orange-brownish in Melzer's reagent. Clamp connections present.

Habit, Habitat, and Distribution: On decayed conifer wood, Wyoming (type) and Idaho, Smith 68312, 68507.

Observations: The pilei are pale yellow as dried, a strong contrast to the dark stipes. The species is most closely related to P. vernalis but the thickened hyphal walls of the gill trama and adjacent pileus trama are unusual in the genus. It is close to P. bridgii but has a gelatinous pileus cutis and smaller cells in the trama of the hymenophore.