The North American Species of Crepidotus

37. Crepidotus avellaneus sp. nov.

Illustrations: Figs. 9, 10, 90.

Pileus 4-12 (15) mm latus, sessilis, ungulatus, orbicularis, albus demum "pinkish buff," vel avellaneus, glabrosus vel albo-villosus. Lamellae albae deinde cinnamomeae, confertae vel paene subdistantes, latae demum medio-latae. Sporae 4.5-7 (7.5) µ globosae, punctatae. Basidia 18-25 x 5-7 µ tetraspora. Pleurocystidia desunt; cheilocystidia 37-60 (70) x 5-10 µ. Cuticula ex hyphis repentibus composita, hyphas erectas et pileocystidia gerens. Fibulae adsunt. Specimen typicum in Herb. Univ. Mich., lectum prope Lewiston, Mich., July 30, 1963, A. H. Smith 66950.

Pileus 4-12(15) mm broad, gregarious, sessile, ungulate, orbicular, often convex, white or whitish becoming pinkish buff, dull cinnamon, or avellaneous, glabrous or frosted with white-villose areas, striatulate when moist. Context watery brownish; odor and taste mild.

Lamellae white, then cinnamon, close or nearly subdistant, broad to medium broad, edges even or becoming white-fimbriate.

Spores 4.5-7 (7.5) µ in diameter, globose, punctate. Basidia 18-25 x 5-7 µ, 4-spored. Pleurocystidia none; cheilocystidia 37-60 (70) x 5-10 µ irregularly cylindric, often slightly bottle-shaped, at times capitate. Gill trama subparallel, hyphae 5-8 µ broad. Pileus trama interwoven, often loosely so. Cuticle of repent hyphae, often bearing scattered, erect, slender hyphae, and, at scattered intervals over the surface, pileocystidia , in dense clusters on the pileus margin. Clamp connections present.

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

Material Studied: MICHIGAN: Smith 37308, 63669, 63672, 63675, 66950 (type, from Lewiston, July 30, 1963), 66952, 67134, 67135, 67136, 67137.

Observations: The avellaneous pileus, frosted with white villosity or pubescence, and the long cheilocystidia are distinctive features of this species.