Stropharia populicola L. Fan, S. Guo & H. Liu, 2021

Liu, Hong, Mao, Ning, Fan, Li & Guo, Shang, 2021, Stropharia populicola (Strophariaceae, Agaricales), a new species from China, Phytotaxa 518 (4), pp. 251-260 : 256-257

Stropharia populicola L. Fan, S. Guo & H. Liu sp. nov. ( Figs. 2 , 3 )

MycoBank:—MB840589

Diagnosis:—differs from other species by the yellowish cap with scaly surface and the presence of the hymenial acanthocytes usually.

Etymology:—‘ populicola’, refers to the substrate of Populus litter.

Holotype:— CHINA. Shanxi Province, Loufan County, Yundingshan Mt. , 1200 m elev., 11 September 2020, on the ground under Populus sp. , H. Liu LH 1314 ( BJTC FM1480 ).

Description:— Pileus 25–40 mm when young, 50–120 mm at maturity, hemispheric at first, without umbo, becoming convex to plane with age, slightly depressed, surface grayish brown (#a9a9a9), brown (#68421b), or yellowbrown (#a5682a) when young, often with light lilac tints (#c8a2bf), changing to yellow-brown (#a5682a) to yellowish finally at maturity, drying, non-sticky when wet, covered with brown squamules, margin incurved, often with partial veil remnants. Pileus context white, up to 20 mm thick. Lamellae adnexed to adnate, grayish purple (#b1b1b1), becoming brown (#68421a) with age, crowded, with grey whitish (#fdfdfd) margin. Stipe central, 40–100 × 12–20 mm, terete, equal, or clavate with a sub-bulbous base; surface white (#ffffff), sparsely or densely fibrillose-squamulose, fibrils and scales usually disappearing with age, until sometimes almost smooth, solid at first, softening with age, and finally fistulose, basal rhizomorphs absent. Annulus sometimes absent, if present, membranous, white, attached at the middle or half of the stipe. Spore print purple-brown.

Basidiospores [30/3/3] 5.5–7.5(–9) × 3.5–5 μm, [Q = (1.30–) 1.50–1.70 (–1.88), Q av = 1.60 ± 0.20], ellipsoid, irregularly ellipsoid or slightly rhomboid in face-view, brown, with a reduced germ-pore, smooth. Basidia 25–30 × 10–12.5 μm, cylindrico-clavate, 2–4 spored, sterigmata usually shorter than 1.5 μm. Lamella edge sterile with crowded cheiloleptocystidia, 32.5–50 × 12.5–17.5 μm, clavate to subfusoid, thin-walled. Three elements occurring on the sides of the gills apart from basidia: (i) Pleurochrysocystidia, abundant, 27.5–32.5 × 7.5–12.5 μm, clavate to pyriforme with or without short mucronate apex, containing amorphous contents yellowish in KOH and Melzer’s reagent, thin-walled; (ii) Pleurocystidia, rare, clavate to subfusoid, up to 42.5 × 15 μm; (iii) Acanthocytes, commonly present in the form of cystidioid structures; the acanthocytes comprises a basal inflated cell from which arises 6–13 projections, 47.5 × 5 μm, and with thickened walls. Hymenophoral trama regularly parallel arrangement, with thin-walled, hyaline hyphae, 5– 10 μm diam. Pilipellis a cutis of hyaline to yellowish hyphae 5–7.5 μm in diam, thin-walled. Squamules on the pileus comprising fascicles of hyphae of 3.5–8.5 μm in diam, thin-walled, yellowish to yellowish brown in KOH. Context hyphae thin-walled, hyaline in KOH, 5–15 μm diam. Stipitipellis parallel arrangement with hyaline hyphae 5–15 μm diam, thin-walled. Caulocystidia absent. Acanthocytes present on the basal mycelium at stipe. Clamp connections present only in basal mycelium at stipe.

Habit, habitat and distribution:—Solitary, scattered, or gregarious on humic soil under forest of Populus sp. , in autumn. Widely distributed from middle to southern Lvliangshan Mts. in Shanxi Province, North China.

Additional specimens examined:— CHINA. Shanxi Province, Xingxian County, Heichashan Mt. , 5 September 2018, on ground under Populus sp. , S. H . Li LH 361 ( HSA361 ); ibid. Loufan County, Yunding Mt. , 11 September 2020, on ground under aspen trees ( Populus spp .), H . Liu LH1311 ( BJTC FM1477 ), LH1317 ( BJTC FM1483 ); ibid. Puxian County, Wulushan Mts. , on ground under broad-leaved trees with Populus sp. nearby, 13 September 2020, H . Liu LH1353 ( BJTC FM1454 ) .

Figures

FIGURE 2. Macroscopic features of Stropharia populicola (BJTC FM1480, holotype). a–b.Basidiomes. Scale bars: a, b= 10 mm. Photos by: Li Fan.

FIGURE 3. Microscopic features of Stropharia populicola (BJTC FM1480, holotype). a. Basidia b. Basidiospores c. Cheiloleptocystidia d. Pleurochrysocystidia and Pleurocystidia e. Acanthocytes. Scale bars: a, b = 5 μm; c, d, e = 10 μm. Drawings by: Ning Mao.