The North American Species of Pholiota
38. Pholiota caespitosa sp. nov.
Illustrations: Text figs. 128-130.
Pileus 3-5 cm latus, convexus demum late convexus, viscidus, fibrilloso-squamlulosus, subalbidus demum pallide luteus, ad marginem appendiculatus. Contextus albus. Lamellae adnato-decurrentes, subdistantes, latae, luteae. Stipes caespitosus, 4-5 cm longus, 6-10 mm crassus, albidus demum luteus, deorsum fibrilloso-squamulosus. Velum copiosum. Sporae 5.5-7.5 x 3.5-4 (4.5) µ. Pleurocystidia ut chrysocystidia, 23-42 x 6-9 µ, clavato-mucronata vel fusoide ventrisosa. Specimen typicum in Herb. Univ. Tenn. conservatum est; legit Anderson County, Tennessee. 31 Oct. 1943, Hesler No. 15908.
Pileus densely caespitose (30-50 in each clump), 3-5 cm broad, convex, viscid, densely fibrillose when young, becoming fibrillose scaly, scales more conspicuous on disc, basic color whitish, scales becoming (at maturity) "chamois," margin incurved and more or less appendiculate. Context firm, moderately thick, white; odor and taste mild (or slightly like Irish potato).
Lamellae adnate-decurrent, finally sinuate, near "honey yellow" to "buckthorn brown," nearly subdistant, medium broad, edges rough (serrulate), many lamellulae present.
Stipe 4-5 cm long, 6-10 mm thick, somewhat flattened from pressure of crowding, whitish, fibrillose-scaly up to ring, naked above, scales "chamois," surface dry, interior hollow. Veil fibrillose, copious, yellow, leaving an evanescent, fibrillose flaring ring.
Spores 5.5-7.5 x 3.5-4 (4.5) µ, dull tawny in KOH, paler and more ochraceous in Melzer's reagent, apex in many spores somewhat truncate from a distinct apical pore, in face view oblong to elliptic or some ovate, in profile slightly bean-shaped to oblong or obscurely inequilateral, wall relatively thin (0.25 µ ±).
Basidia 18-23 (24-35) x 5-7 µ, variable in length, 4-spored, clavate hyaline in KOH, yellowish in Melzer's reagent. Pleurocystidia 23-42 x 6-9 µ, clavate-mucronate to fusoid-ventricose, rarely merely clavate, apex subacute to obtuse, wall smooth thin and hyaline, content as revived in KOH with the typical hyaline refractive inclusion of chrysocystidia, refractive body merely yellowish in Melzer's reagent. Cheilocystidia 20-32 x 5-9 µ, utriform, fusoid-ventricose to subfusoid, hyaline to yellowish in KOH, walls smooth, thin, hyaline, content homogeneous. Caulocystidia 23-35 x 5-9 µ, clavate to narrowly subfusoid, usually remaining agglutinated to stipe tissue in KOH mounts, thin-walled, hyaline to yellowish and content homogeneous.
Gill trama of a floccose central strand of parallel hyphae 5-15 µ diam.; walls thin, smooth, hyaline to yellowish, somewhat refractive; subhymenium of narrow gelatinous to subgelatinous hyphae hyaline in KOH. Pileus cutis a gelatinous pellicle of mostly non-gelatinous hyphae 3-6 µ diam. with very pale ochraceous smooth walls; hypodermium of floccose hyphae with smooth to asperulate darker ochraceous-brown walls, hyphae 4-10 µ diam. Context hyphae hyaline to ochraceous, smooth, the hyphal cells inflated greatly in age. Stipe hyphae perfectly hyaline in KOH except for the agglutinated caulocystidia and the narrow cells which bear them, both ochraceous in KOH. All hyphae inamyloid. Clamp connections present.
Habit, Habitat, and Distribution: Densely caespitose on sawdust. Anderson County, Tenn. Oct. 31, 1943. Hesler 15908 type.
Observations: This is a most interesting species in a number of ways, particularly in that it is intermediate between sect. Pholiota and Sect. Kuehneromyces since the spores, at least many of them are sufficiently truncate to place the species in the latter group, and the species is clearly related to P. veris. The distinctive field features include the densely caespitose habit, its whitish fibrillose scaly pileus, the yellowish scales, yellow gills and white stipe which does not darken in KOH in the apical area.