The North American Species of Crepidotus

95. Crepidotus ellipsoideus sp. nov.

Illustration: Fig. 167.

Pileus (6)10-25 mm latus, sessilis, conchatus, reniformis, flabelliformis, albus deinde ochraceus demum coriaceus, fibrillosus. Lamellae confertae vel paene subdistantes, medio-latae, albae deinde alutaceae. Sporae (5.5) 6-8 x (4) 4.5-5.5 µ, ellipsoideae demum ovoideae, punctatae. Basidia 24-35 x 6-8 µ, di- et tetraspora. Pleurocystidia desunt; cheilocystidia 26-45 (66) x 5-12 (17) µ, contorta. Cuticula ex hyphis repentibus composita, hyphas erectas, sinuosas et in spiram volutas, 3-6 µ latas. Fibulae adsunt. Specimen typicum in Herb. Univ. Mich., lectum prope Pellston Hills, Mich., July 16, 1961, 0. Miller 1051.

Pileus (6) 10-25 mm broad, sessile, dry, conchate, reniform, flabelliform, white or whitish, at times ochraceous or watery buff in age, pubescent to fibrillose, margin pruinose, inrolled. Context thin, white; odor and taste not distinctive.

Lamellae close or nearly subdistant, medium broad, white then alutaceous, edges even.

Spores (5.5) 6-8 x (4) 4.5-5.5 µ ellipsoid or somewhat ovoid, inequilateral in profile, punctate, pale tawny in 2% KOH. Basidia 24-35 x 6-8 µ, 2-4-spored. Pleurocystidia none; cheilocystidia 26-45 (66) x 5-12 (17) µ, ventricose, clavate, crooked, contorted, at times forked. Gill trama interwoven to subparallel, hyphae 5-9 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, bearing a turf of crooked and coiled hyphae, 3-6 µ broad. Clamp connections present.

Habit, Habitat, and Distribution: On hardwood, rarely on coniferous wood, Canada, Michigan, Colorado, Idaho, Indiana, Tennessee, June-September.

Material Studied: COLORADO: Smith 52722; IDAHO: Smith 65600; INDIANA: Cooke 32846; MICHIGAN: Miller 1049, 1050, 1051, type (MICH), from Pellston Hills, collected by O. Miller, July 16, 1961; Smith 49806, 57075, 57086, 57087b, 57090, 57091, 57092, 57093, 57887, 63577, 63582, 63586, 63671, 66820, 66845; TENNESSEE: Hesler 8083, 12778; ONTARIO: Kelly 936 (MICH).

Observations: This species is characterized by its white pileus, moderately small, punctate spores, contorted cheilocystidia, and crooked to coiled hyphae on the surface of the pileus. It appears to be near C. sphaerosporus, which has distinctly broader spores.