The North American Species of Pholiota

120. Pholiota pseudograveolens sp. nov.

Illustrations: Text figs. 508-510; pl. 58.

Pileus 6-7.5 cm crassus, late convexus demum planus, subviscidus, ad centrum sordide luteo-brunneus, ad marginem laete citrinus, glaber. Contextus crassus, firm us, laete citrinus demum olivaceobrunneus; sapor mitis; odor fragrans. Cum "FeSO," olivaceus, "Guaiac" deinde caeruleus. Lamellae laete luteae demum subfulvae, adnatae, late, confertae. Stipes 4-6 cm longus, 9-12 mm crassus, deorsum sordide luteo-brunneus, sursum citrinus. Sporae 6-8 x 3.5-4 µ. Pleurocystidia crassotunicata. Specimen typicum in Herb. Univ. of Mich. conservatum est; legit prope Proud Lake Recreation Area, Oakland Co., Michigan. Sept. 3, 1966, Smith 73302.

Pileus 6-7.5 cm broad, expanded plane at maturity, broadly convex when young, glabrous, subviscid when fresh but soon dry, color near "bister" on disc or dull "tawny," (dull to brighter yellow brown), near the margin lemon yellow, opaque when moist or faded. Context thick and firm, lemon chrome near margin, near olive to olive-brownish in disc, odor strongly fragrant as in Cortinarius percomis, taste mild, with FeSO4 olive, with Guaiac quickly blue.

Lamellae bright yellow, slowly becoming buckthorn brown from spores, broadly adnate, tapered to margin of pileus, broad, close, edges crenulate.

Stipe 4-6 cm long, 9-12 mm thick, equal, chrome yellow within above, becoming bister in cortex over the base and finally over all; surface thinly fibrillose, upper part lemon yellow, basal mycelium orange in age.

Spores 6-8 x 3.2-3.8 (4) µ, smooth, with a minute but distinct apical pore, shape in face view ovate to nearly elliptic, in profile somewhat narrowly inequilateral; color in KOH dull cinnamon and about the same in Melzer's reagent; wall about 0.25 µ thick.

Basidia 4-spored, 18-22 x 5-6.5 µ, narrowly clavate, yellowish in KOH, dull ochraceous orange in Melzer's reagent. Pleurocystidia 38-65 (76) x 9-15 µ basically fusoid-ventricose but neck elongate and with swellings and constrictions, apex typically obtuse; smooth; wall thin at first but soon thickened to 0.6-1.2 µ at upper portion of ventricose part and in adjacent part of neck, content of some cystidia yellow and coagulated even in fresh specimens, coagulated content in revived sections (in KOH) orange brown but soon fading to yellowish, in Melzer's reagent the content nearly colorless, many originating from the parallel hyphae of the gill trama. Cheilocystidia 28-40 x 7-12 µ, clavate to fusoid ventricose but the necks short, walls thin, smooth, yellowish in KOH. Caulocystidia present merely as the occasional more or less appressed clavate end-cell of a surface hypha, walls yellowish in KOH.

Gill trama consisting of a broad band of parallel hyphae with more or less inflated elongate hyphal cells having thin to scarcely thickened walls yellowish to hyaline in KOH as revived, walls smooth; subhymenium a gelatinous band of narrow (2-3 µ) much branched hyphae. Pileus cutis of interwoven narrow (2-4 µ) hyphae yellow to hyaline in KOH, outline distinct but imbedded in a gelatinous matrix, hypodermium of rusty to orange-brown hyphae with inflated cells to 12-20 µ diam., walls smooth to incrusted. Context hyphae yellow in KOH (fresh or revived specimens), typically thin walled, closely interwoven and hyphal cells inflated. Clamp connections present.

Habit, Habitat, and Distribution: Gregarious on decaying aspen log. Proud Lake Recreation Area, Sept. 3, 1966. Smith 73302, type.

Observations: This species may be more closely related to P. graveolens than any other species, but the thick-walled cystidia separate it at once. The strong odor, tendency of the cystidia to develop thickened walls, the orange mycelium at the base of the stipe on old basidiocarps, and the dull brown pileus disc compared to the bright yellow margin are a distinctive set of features.