The North American Species of Crepidotus

25. Crepidotus conchatus sp. nov.

Illustrations: Figs. 74, 75.

Pileus 4-10 mm latus, sessilis, albus, conchatus, villosus vel fibrillosus, glabrescens. Lamellae albae deinde pallido-cinnamomeae, latae demum medio-latae, confertae. Sporae 4.5-5.5 µ, globosae, punctatae. Basidia 20-28 x 5-7 µ, di- et tetraspora. Pleurocystidia desunt; cheilocystidia 26-62 x 5-10 µ. Cuticula ex hyphis repentibus composita, plerumque hyphas erectas gerens; pileocystidia cheilocystidiis similia. Fibulae adsunt. Specimen typicum in Herb. Univ. Mich.; lectum in Bois Blanc Island, Michigan, July 21, 1961, A. H. Smith 63600.

Pileus 4-10 mm broad, sessile, white, more or less dingy in age, conchate, somewhat villose or fibrillose, glabrescent. Context whitish.

Lamellae white then pale cinnamon, broad or medium broad, close or moderately close, thin.

Spores 4.5-5.5 µ in diameter, globose, punctate. Basidia 20-28 x 5-7 µ, 2-4-spored. Pleurocystidia none; cheilocystidia 26-62 x 5-10 µ, versiform: cylindric, clavate, ventricose, rarely septate. Gill trama subparallel or slightly interwoven, hyphae 4-10 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, usually bearing erect hyphae and, at times, pileocystidia resembling the cheilocystidia. Clamp connections present.

Habit, Habitat, and Distribution: On hardwood log, Michigan, July-August.

Material Studied: MICHIGAN: Smith 63600 (type from Bois Blanc Island, July 21, 1961), 66265.

Observations: This species is distinguished by its white, conchate pileus, broad gills, and small spores. Its broad gills exclude it from C. applanatus, and its small spores separate it from C. malachius.