The North American Species of Crepidotus
111. Crepidotus amygdalosporus Kühner, Bulletin Soc. Nat. Oyonnax 8: 74. 1954.
Pileus 5-15 (30) mm broad, sessile, ungulate, conchoid, to flabelliform, white, pubescent or tomentose, base byssoid, dry, margin inrolled, even. Context thin; taste mild.
Lamellae white, becoming brown, close or nearly subdistant, narrow to medium broad.
Spores in deposit: dull cinnamon; spores 7-9.5 (11) x (4) 4.5-5.5 µ, ellipsoid, inequilateral in profile, punctate. Basidia 20-27 x 5-7 µ, 4-spored. Pleurocystidia none; cheilocystidia (23) 28-52 (90) x 5-10 µ, clavate, ventricose, flask-shaped, more rarely subfusoid or knobbed. Gill trama subparallel to slightly interwoven, hyphae 4-10 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, or at times not sharply differentiated, the surface bearing a turf of colorless hyphae, 2.5-6 µ broad. Clamp connections present.
Habit, Habitat, and Distribution: On hardwood, rarely on conifer, Maine, Massachusetts, Michigan, North Carolina, Washington, June-December; also Europe.
Material Studied: MAINE: Bigelow (MASS) 10156, 10337; MASSACHUSETTS: Bigelow (MASS) 8232; MICHIGAN: Bigelow (MICH) 200; Bas (MICH) 527; Smith 20398, 49805, 50942, 63640, 66629, 66905, 67202, 67374; Thiers 3092 (MICH); NORTH CAROLINA: Hesler 25540; WASHINGTON: Smith 14558, 17848, 29546; NETHERLANDS: Bas (L), from near Amsterdam, leg. & det. E. L. v. Waveren, Dec. 8, 1960.
Observations: The distinctive characteristics of C. amygdalosporus include a white pileus with straight hyphae on its surface, relatively long, punctate spores, regularly shaped cheilocystidia, and lamellae which are white then brownish.