The North American Species of Pholiota

46. Pholiota obscura sp. nov.

Pileus 1-2.2 cm latus, obtuse conicus, demum planus, lubricus demum viscidus, obscure "ochraceous tawny" demum "cinnamon buff." Caro concolor; odore et gustu mitis. Lamellae adnatae, latae, subdistantes, "ochraceous tawny," leviter se obscurantes naturae. Stipes 2-3 cm longus, 2-3 mm crassus, infra obscure brunneus, supra furvus. Velum fugax, cineraceo-coriaceum. Sporae 7-9 (10) x 3.8-4.5 (5) µ, ellipsoideae vel ovoideae, leves, truncatae. Pleurocystidia desunt. Cheilocystidia 25-44 x 5-8 µ, subfusoidea vel ampullacea, cervice leviter vel constricta. Cuticula cingulum angustum gelatinosum. Caulocystidia 25-37 x 5-7 µ, cheilocystidiorum similia. Specimen typicum in Herb. Univ. Mich. conservatum est; legit prope McCall, Idaho, June 23, 1962, Smith 65011.

Pileus caespitose, 1-2.2 cm broad, obtusely conic with a straight margin, expanding to plane or the margin slightly uplifted and wavy, surface lubricous to viscid and shining, translucent striate to disc when moist and then dull ochraceous tawny, fading to cinnamon buff. Context thin, fragile, watery, concolorous with surface, -odor and taste none, FeSO4 and KOH both no reaction.

Lamellae broad, adnate, subdistant, ochraceous tawny and not changing color much on maturing, edges fimbriate.

Stipe 2-3 cm long, 2-3 mm thick, equal, watery, fragile, dark reddish brown below, tawny above, at first faintly fibrillose from grayish buff veil fibrils, veil very thin and soon evanescent, apex faintly pruinose and at first striate.

Spores 7-10 x 3.5-4.5 µ, smooth, wall very slightly thickened (about 0.25 µ), apex truncate from an apical pore, in face view distinctly ovate varying to elliptic, in profile somewhat inequilateral, a small number slightly compressed and rarely one slightly angular; in KOH cinnamon to tawny, in Melzer's reagent slightly paler.

Basidia 4-spored, 20-24 x 6-8 µ, hyaline to yellowish in KOH and Melzer's reagent, clavate. Pleurocystidia present in the hymenium between the gills (rarely on gill surface), 20-28 x 7-12 µ, broadly fusoid-ventricose to subclavate or elliptic, thin-walled, hyaline in KOH, content homogeneous. Cheilocystidia (20) 26-45 x 5-10 µ, utriform, fusoid-ventricose or ventricose-rostrate, wall in neck flexuous, hyaline in KOH, wall very slightly thickened to thin, smooth, cell content homogeneous as revived in KOH.

Gill trama of narrow (3-8 µ) parallel to interwoven hyphae, walls thin, pale cinnamon to nearly hyaline in KOH, yellowish in Melzer's reagent; subhymenium non-gelatinous, in age cellular from inflation of cells. Pileus cutis a thin gelatinous layer in which are imbedded hyaline tubular hyphae 2-6 µ diam. (in age the layer often obliterated); hypodermial zone of inflated (8-15 µ ±) hyphal cells with ochraceous to rusty brown walls as revived in KOH, the walls thin and color fading as the mount stands. Clamp connections present. Some amyloid debris present in places in a mount but all hyphae inamyloid.

Habit, Habitat, and Distribution: Caespitose on rotten wood, Idaho, June, Smith 65001 type, 58682, 65043, 65131, 65154, all from near McCall, Idaho.

Observations: In Smith 65131 the hymenophoral trama when fresh became pale rusty brown to dark ochraceous in KOH. The type, however, was not tested when fresh. Also, the gills appeared close when fresh but as dried there is no appreciable difference in gill spacing between it and other collections. We hesitate to emphasize the presence of pleurocystidia between the gills as an important taxonomic character. P. obscura is distinct from P. vernalis by its broad gills which are typically subdistant, P. galerinoides has abundant pleurocystidia, incrusted hyphae in the pileus (hypodermial zone) and small cheilocystidia.