The North American Species of Pholiota

101. Pholiota barrowsii sp. nov.

Illustrations: Text figs. 202-203.

Pileus 4-8 cm latus, late convexus, viscidus, squamosus, luteus; squamae subbfulvae. Contextus pallidus demum pallide luteus. Lamellae latae, adnatae, confertae, pallide ochracea demum luteo brunneae. Stipes 4-9 cm longus, 5-12 mm crassus, solidus, deorsum fulvus et fibrillose squamosus vel flocculosius, sursum sericeus. Sporae 5-6.5 x 3-3.5 µ. Pleurocystidia 30-56 (60) x 7-14 µ, clavata vel clavato-mucronata. Cheilocystidia 20-28 x 5-9 µ. Specimen typicum in Herb. Univ. of Mich. conservatum est; legit prope Santa Fe, New Mexico, Aug. 1957. Chas. Barrows 504.

Pileus 4-8 cm broad, convex becoming nearly plane, surface covered with coarse dry scales as in P. squarrosa, the scales dingy tawny brownish as dried, yellow ground color reminding one of P. squarroso-adiposa and near ochre yellow as dried, viscid in age as scales wear away from the thick gelatinous pellicle. Context pallid becoming yellowish and as dried pale buff, odor and taste mild.

Lamellae broad, bluntly adnate, in age adnexed, close, pallid ochraceous becoming near "buckthorn brown" (fairly dark clay-color), edges even.

Stipe 4-9 cm long, 5-12 mm thick, equal or nearly so, solid, becoming rusty brown over basal area, melleous above or paler, lower three fourths covered by copious shaggy floccose patches or zones of veil remnants terminating at an annular zone, paler and silky above, as dried the veil remnants yellowish.

Spores 5-6 (6.5) x 3-3.5 µ, smooth, apical pore not evident; shape in face view elliptic to ovate, in profile slightly bean-shaped to elliptic, in KOH about "cinnamon-buff" (pale clay-color), in Melzer's reagent, paler (nearly hyaline): wall less than 0.25 µ thick.

Basidia 4-spored, 15-22 x 4-5 µ, clavate, hyaline in KOH, yellowish in Melzer's reagent. Pleurocystidia 35-56 (60) x 7-14 µ, clavate to clavate mucronate, with a long slender pedicel, wall thin and smooth; content homogeneous but opaque and somewhat refractive, in a few dark ochraceous. Cheilocystidia 1) clavate, 20-28 x 5-9 µ, hyaline, thin-walled smooth, content homogeneous; 2) similar to pleurocystidia. Caulocystidia (none observed on material available).

Gill trama with a floccose interwoven central strand, the hyphal cells enlarged, smooth, in KOH yellowish to hyaline and wall slightly thickened (laminate) or thin; subhymenium a gelatinous layer of narrow 1.5-2.5 µ interwoven hyphae, giving off gelatinous branches ending in basidia and these also tending to cause hymenium to be almost trichodermium-like (composed of hyphal branches, not single cells in a palisade). Pileus cutis an extremely thick layer of gelatinous narrow (1.5-3 µ) hyaline hyphae with walls lacking a sharp outline as revived in KOH; hypodermial region of dull ochraceous floccose hyphae 6-14 µ diam.; walls smooth, thin to slightly thickened, pigment present in the wall. Context hyphae of wide (8-18 µ) smooth hyphae with thin to slightly thickened (laminated) walls near subhymenium, yellow in KOH, reddish in Melzer's reagent when first mounted but soon fading to dull ochraceous. Clamp connections present.

Habit, Habitat, and Distribution: Caespitose on aspen, in the mountains near Santa Fe, N. Mexico 8000 ft. elevation. Aug. 1957. Chas. Barrows 504, type.

Observations: This species has the veil of P. squarrosoides but the veil is yellow, not whitish; it has the colors of P. squarroso-adiposa but the pileus is scaly as in P. squarrosa, for which it was mistaken in the field. It has a thick gelatinous pellicle over the pileus which of course excludes that species. The conspicuous pleurocystidia are a striking feature of the species. Although they are of the characteristic shape of chrysocystidia (clavate-mucronate) as revived in KOH they lack the amorphous-refractive inclusion. They closely resemble those of P. squarrosoides in all features except size. The scales of the pileus in both, as revived in KOH, have the hyphal cells rusty brown, and with thickened walls to about 1 µ, but in P. barrowsii the cells are elongate and mostly smooth, in P. squarrosoides more of the cells have incrustations on the walls and the cells tend to be isodiametric or nearly so. If one were given to speculation it would be a simple matter to visualize P. barrowsii as a hybrid between P. squarroso-adiposa and P. squarrosoides.