The North American Species of Crepidotus

4. Crepidotus unicus sp. nov.

Illustration: Fig. 37.

Pileus 7-12 mm latus, cuneatus demum semi-orbicularis, cineraceus, fibrillosus, lubricus, margine planus. Lamellae brunneae, angustae demum medio-latae, confertae vel subdistantes. Sporae 4.5-5.5 µ, globosae, perraro subovoideae, brunneae, palam punctato-echinulatae. Pleurocystidia desunt; cheilocystidia 17-40 x 7-10 µ. Pilei trama duplex: pars interior decima usque quarta ex intertextis hyphis, pars exterior e laxe implicatis hyphis composita. Fibulae desunt. Specimen typicum in Herb. Univ. Tenn.; lectum in Great Smoky Mts. National Park, Tenn., Aug. 9, 1952, L. R. Hesler 20503.

Pileus 7-12 mm broad, cuneate to semi-orbicular, grayish-white, appearing somewhat fibrillose under lens, lubricous when wet, margin even.

Lamellae radiating from a lateral point, brown, narrow or medium broad, close or nearly subdistant.

Stipe none; pileus attached laterally, at times by a prolongation of one side.

Spores 4.5-5.5 µ, globose, more rarely subovoid, conspicuously punctate-echinulate, brown. Pleurocystidia none; cheilocystidia 17-40 x 7-10 µ, clavate, ventricose, often capitate or forked or knobbed and contorted. Gill trama subparallel, hyphae 5-8 µ broad. Pileus trama duplex: the inner one-tenth to one-fourth composed of non-gelatinous, closely interwoven hyphae, the outer three-fourths to nine-tenths of very loosely tangled hyphae. Cuticle of repent hyphae. Clamp connections none.

Habit, Habitat, and Distribution: On conifer bridge timber, Tennessee, August.

Material Studied: TENNESSEE: Hesler 20503, type, Alum Cave Parking Area, Great Smoky Mts. National Park, August 9, 1952.

Observations: This is a unique species because of the combination of globose spores, stratose pileus trama, and lack of clamp connections.