The North American Species of Crepidotus

19. Crepidotus coloradensis sp. nov.

Illustration: Fig. 61.

Pileus 5-25 mm latus, sessilis, flabelliformis demum reniformis, albus deinde "pinkish buff," vel cinereo-coriaceus, villosus demum fibrillosus, siccus. Lamellae albae demum coriaceae vel brunneae, latae, subdistantes. Sporae 6-7.5 (8) x 4-5 µ, ellipsoideae, planae. Basidia 20-30 x 5-7 (8) µ, tetraspora. Pleurocystidia desunt; cheilocystidia (20) 45-67 x (2) 6-9 µ. Cuticula ex hyphis repentibus composita, gerens caespitem ex hyphis sine colore compositum. Fibulae desunt. Specimen typicum in Herb. Univ. Mich.; lectum prope Ophir, Colorado, Aug. 26, 1956, A. H. Smith 52889.

Pileus 0.5-2.5 cm broad, sessile, white, finally becoming pinkish buff, or more rarely grayish buff, villose to fibrillose, dry, flabelliform to reniform. Context whitish; odor and taste none or slight.

Lamellae white, becoming buff, or near wood brown, broad, subdistant or nearly so, edge white fimbriate.

Spores 6-7.5 (8) x 4-5 µ, ellipsoid in face view, inequilateral in profile, smooth, pale ochraceous tawny in KOH. Basidia 20-30 x 5-7 (8) µ, 4-spored. Pleurocystidia none; cheilocystidia (20) 45-67 x (2) 6-9 µ, usually more or less subulate or flask-shaped with a neck, at times filamentous to clavate, flexuous, the neck occasionally branched. Gill trama interwoven, hyphae 4-12 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, bearing a turf of colorless hyphae 1.5-2.5 (5) µ broad. Clamp connections none.

Habit, Habitat, and Distribution: On aspen, Michigan, Colorado, and New Mexico, June-October.

Material Studied: COLORADO: Smith 51637, 51803, 52191, 52460, 52461, 52666, 52889 (type, from Ophir, Aug. 26, 1956); MICHIGAN: Smith 32300, 49598, 50628; NEW MEXICO: Barrows 438A (MICH).

Observations: The pileus is white but may become some shade of buff. The smooth, medium-small spores, and more or less subulate to flask-shaped cheilocystidia are distinctive. The spores separate it from both C. herbarum and C. versutus.