The North American Species of Crepidotus

100. Crepidotus eburneus sp. nov.

Illustrations: Figs. 24, 172, 194.

Pileus 5-22 mm latus, sessilis, ungulatus deinde applanatus, albus, immutabilis, fibrillosus, margine incurvatus. Lamellae albae deinde obscuro-luteae, confertae, latae, vel medio-latae, ventricosae. Sporae 7-11 x 4-4.6 µ, ellipsoideae, extremis decrescentes, punctatae. Basidia 22-27 x 5-6 µ tetraspora. Pleurocystidia desunt; cheilocystidia (18) 27-43 x 5-10 µ. Cuticula ex hyphis repentibus composita, hyphas sinuosas vel in spiram volutas sine colore gerens, 3-5 µ latas. Fibulae adsunt. Specimen typicum in Herb. Univ. Mich.; lectum in Ogemow Reserve, Mich., Sept. 4, 1963, A. H. Smith 67371.

Pileus 5-22 mm broad, sessile, ungulate then expanding, pure white and remaining so when dried, densely white-silky-fibrillose, margin more or less wavy, incurved. Context thin, white.

Lamellae white then dingy clay color, close or moderately so, ventricose, broad to medium broad, edges fimbriate.

 Spores 7-11 x 4-4.6 µ, slender-ellipsoid, ends more or less pointed, inequilateral in profile, punctate. Basidia 22-27 x 5-6 µ, 4-spored. Pleurocystidia none; cheilocystidia (18) 27-43 x 5-10 µ clavate, obclavate, slightly pyriform, ventricose, cylindric, slightly flexuous. Gill trama subparallel, hyphae 4-6 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, bearing a turf of colorless, crooked or coiled hyphae, 3-5 p broad. Clamp connections present.

Habit, Habitat, and Distribution: On hardwood, Michigan, September.

Material Studied: MICHIGAN: Smith 67371, type, from Ogemaw Reserve, Sept. 4, 1963.

Observations: The snow white pileus remains so after being dried. The yellowish brown, slender spores, and the crooked or coiled, epicuticular hyphae also distinguish it.