The North American Species of Pholiota
187. Pholiota gruberi sp. nov.
Illustrations: Text figs. 421-424.
Pileus 2-5 cm latus, late convexus, glaber, viscidulus, rufo-brunneus. Lamellae confertae, latae adnatae. Stipes 3-5 cm longus, 3-6 mm crassus, aequalis, sursum subpruinosus, deorsum sparse fibrillosus, sordide pallide luteus. Sporae 7-9 x 3.5-4 µ. Pleurocystidia 50-70 x 9-14 µ fusoide ventricosa, ad apicem obtusa vel late rotundata. Cheilocystidia 35-48 x 9-15 µ, utriformia. Specimen typicum in Herb. Univ. of Mich. conservatum est; legit prope Lewiston, Idaho, 2 Juni 1943, Wm. B. Gruber 41.
Pileus 2-5 cm broad, broadly convex with a decurved margin, thinly viscid and soon dry (but pellicle distinct) glabrous, color as dried dull pinkish buff over disc with redder tones near and on margin (reddish brown fresh—Gruber). Context pallid, odor and taste mild to slightly mealy.
Lamellae close, broad, adnate becoming slightly decurrent, seceding in age, color when young not known, dingy cinnamon when mature, edge even to slightly flocculose.
Stipe 3-5 cm long, 3-6 mm thick, equal, yellowish to buff and merely dingy buff as dried, not darkened appreciably at base when dried, apex faintly pruinose, appressed fibrillose-downward, veil very thin (color not known).
Spore print about cinnamon-brown. Spores 7-9 x 3.5-4 µ, smooth, apical pore present and distinct; shape in face view narrowly elliptic to narrowly ovate, in profile obscurely inequilateral to subelliptic; wall about 0.3 µ thick; color in KOH dark cinnamon, in Melzer's paler and more ochraceous; with a distinct apiculus.
Basidia 18-23 x 6-7.5 µ clavate, 4-spored, yellowish to hyaline in KOH, yellowish in Melzer's reagent. Pleurocystidia abundant, 50-70 x 9-14 µ, fusoid ventricose with obtuse to rounded apex, walls smooth thin and hyaline in KOH, and in Melzer's varying to slightly yellowish; content homogeneous, yellowish to hyaline in KOH. Cheilocystidia abundant, 35-48 x 9-15 µ, utriform, thin-walled, smooth, mostly hyaline in KOH. Caulocystidia scattered to rare and more or less like the cheilocystidia.
Gill trama of a central area of subparallel floccose hyphae the cells greatly inflated, hyaline to yellowish in KOH with walls thin and smooth; subhymenium of gelatinous branched narrow (2 µ ±) hyaline hyphae forming a rather wide band. Pileus cutis a thin layer of loosely tangled ochraceous gelatinous narrow (1.5-2 µ) hyphae (revived in KOH); hypodermium very well defined, of floccose hyphae the cells 8-20 µ wide, bright fulvous in KOH and with distinct incrusting patches of pigment adhering. Context hyphae of greatly inflated cells, walls yellowish to hyaline in KOH, thin and smooth. All hyphae inamyloid. Clamp connections present.
Habit, Habitat, and Distribution: Caespitose in masses under the needle cover under Larix occidentalis, near Lewiston, Idaho. June 2, 1943, Wm. B. Gruber 41, type.
Observations: The vernal appearance and the stature of this species remind one of the complex of variants around Hebeloma maesophaeum but the microscopic features clearly place the fungus in Pholiota subg. Flammuloides. The relatively long narrow spores, abundant utriform cheilocystidia smaller than the pleurocystidia, manner of fruiting and occurrence under larch in relatively dry situations distinguish it. The longer narrow spores distinguish it from P. subcarbonaria.