The North American Species of Pholiota

122. Pholiota olivaceophylla sp. nov.

Illustrations: Text figs. 266-267.

Pileus 6-11 cm latus, late convexus, pallide luteus, viscosus, contextus albus. Lamellae olivaceae, confertae, latae. Stipes 6-12 cm longus, 10-15 mm crassus, fibrillosus, anguste clavatus. Sporae 6-8 x 3.4-4.5 µ. Pleurocystidia 40-70 x 9-12 µ, fusoide ventricosa, rare crassitunicata. Specimen typicum in Herb. Univ. Mich. conservatum est; legit Wm. B. Cooke 29502, Mt. Shasta, Calif. June 1954.

Pileus 6-11 cm broad, expanding to nearly plane, yellowish tan to whitish, with a yellowish slimy covering. Context white; odor somewhat nutty, taste none.

Lamellae adnate, at first olive, then brown, close, broad (10 mm more or less).

Stipe 6-12 cm long, 10-15 mm thick, fibrillose, inflated below to 25 mm, with conspicuous white rhizomorphs.

Spores 6-8 x 3.5-4.5 µ, smooth, apical pore minute, ovate to elliptic in face view, in profile obscurely inequilateral to slightly bean-shaped, tawny in KOH, about the same color or paler revived in Melzer's reagent, wall thin (± 0.3 µ).

Basidia 20-25 (28) x 5-7µ, 4-spored, narrowly clavate, yellowish in KOH and Melzer's reagent. Pleurocystidia abundant, 45-70 x 9-20 µ, yellow to hyaline in KOH, content homogeneous, thin-walled or rarely the wall up to 0.5 µ thick, fusoid-ventricose to ventricose-rostrate with the neck narrowest at the apex of the ventricose part, neck usually filled with a homogeneous "colloidal" substance, smooth, apex obtuse. Cheilocystidia 43-52 x 12-17 µ, fusoid-ventricose to subellipsoid-pedicellate, yellow to hyaline in KOH, content homogeneous, at times the neck short and apex somewhat capitate, a few seen with particles of debris adhering. Caulocystidia none.

Gill trama a central area of greatly inflated hyphae more or less interwoven, the walls thin, smooth and yellowish to hyaline in KOH; subhymenium cellular and not gelatinous in freshly matured specimens, cells small (4-7 µ) and the layer inconspicuous. Pileus cutis an exceedingly thick layer of hyaline gelatinous hyphae 2-5 µ diam. with smooth walls disintegrating almost completely; hypodermium a layer of smooth bright ochraceous hyphae the walls thickened slightly and refractive (in KOH) but not incrusted. Context hyphae smooth, yellowish to hyaline in KOH, cells 8-15 µ diam., inflated. Clamp connections present. All hyphae inamyloid.

Habit, Habitat, and Distribution: On and near very rotten Shasta fir log, Mt. Shasta, Calif. June 1954. Wm. B. Cooke 29502, type.

Observations: This species is unusual because of the hymenium which is cellular and not gelatinous, though on standing in KOH it becomes rather transparent and possibly subgelatinous. It is in sharp contrast, however, to the branched-filamentous hyphal structure typical of subg. Flammuloides. The pleurocystidia vary from narrowly to broadly ventricose, and in a few the wall may be seen to measure up to 1.5µ thick, but most remain thin-walled. It is the manner in which the neck is constricted just at the apex of the ventricose part in many of the cystidia which is distinctive. It has the stature of P. sububrica. The colors are much paler fresh than in P. castanea, but the two are related by the nongelatinous subhymenium.