The North American Species of Crepidotus

85. Crepidotus occidentalis sp. nov.

Illustration: Fig. 158.

Pileus 10-30 mm latus, albus, immutabilis,flabelliformis, pubescens, margine incurvatus. Lamellae confertae, latae vel medio-latae. Sporae 7-10 x 5-6 (7) µ, ellipsoideae vel subovoideae, planae. Basidia 26-34 x 7-9 µ, tetraspora. Pleurocystidia desunt; cheilocystidia 33-55 x 4-7 µ. Cuticula ex hyphis repentibus composita, hyphas erectas gerens. Fibulae adsunt. Specimen typicum in Herb. Univ. Mich.; lectum prope Lake Crescent, Wash., June 4, 1939, A. H. Smith 14051.

Pileus 10-30 mm broad, pure white and remaining so when dried, flabelliform, dry, minutely pubescent, margin incurved. Context white; odor and taste not recorded.

Lamellae adnate to the apex of a pseudostipe if present, or converging to a point, close, broad to moderately broad, edges fimbriate.

Pseudostipe at times present.

Spores 7-10 x 5-6 (7) µ, ellipsoid to subovoid, slightly inequilateral in profile, smooth, brown (dark clay color). Basidia 26-34 x 7-9 µ, 4-spored. Pleurocystidia none; cheilocystidia 33-55 x 4-7 µ, filamentous, cylindric, subventricose, or subclavate. Gill trama subparallel, hyphae 4-9 µ broad. Pileus trama interwoven, with large interspaces. Cuticle of repent hyphae, bearing a turf of straight, long, slender hyphae. Clamp connection present on the trichodermial hyphae.

Habit, Habitat, and Distribution: On Alnus, Washington, June.

Material Studied: WASHINGTON: Smith 14051 (type, from Lake Crescent, June 4, 1939), 14558.

Observations: This differs from C. betulae in its larger spores and lack of a gelatinous cuticle. It is related to C. lundellii and C. antillarum, neither of which remains pure white at maturity or on drying.