Amauroderma concentricum J. Song, Xiao L. He & B.K. Cui, 2016

Song, Jie, Xing, Jia-Hui, Decock, Cony, He, Xiao-Lan & Cui, Bao-Kai, 2016, Molecular phylogeny and morphology reveal a new species of Amauroderma (Basidiomycota) from China, Phytotaxa 260 (1), pp. 47-56 : 52-54

Amauroderma concentricum J. Song, Xiao L. He & B.K. Cui , sp. nov. ( Fig. 3 )

MycoBank no.: MB 816517

Diagnosis:— Amauroderma concentricum is characterized by a yellowish brown to reddish brown, concentrically zoned pileal surface, a white pore surface unchanged when bruised, single to multiple stipes, small pores (4–5 per mm), subglobose to globose and double-walled basidiospores, 8–9.2 × 7.2–8 Μm.

Type:— CHINA. Sichuan Prov.: Mianning County, Lingshansi Park, on ground of angiosperm forest, 13 September 2015, Cui 12644 (holotype, BJFC! isotype in H!).

Etymology:— Concentricum (Lat.) referring to the concentrically zoned pileal surface.

Description:—Basidiomata annual, centrally stipitate (mesopodal), coriaceous to corky. Pileus single, suborbicular to circular, umbelliform, up to 11 × 10 cm wide, 8 mm thick. Pileal surface dull, glabrous, yellowish brown to reddish brown when fresh, clay buff to fuscous when dry, densely concentrically zoned and slightly irregularly radially furrowed. Margin acute and involute when dry. Stipe single to multiple, up to 7 cm long, 5 mm in diam., cylindrical to slightly flattened at base, the surface concolorous with the pileus surface, with a homogeneous, spongy, white context. Pore surface white when fresh, pale straw yellow when dry, unchanged on bruising. Pores round to angular, 4–5 per mm; dissepiments thin, entire. Context homogeneous, white to cream, without dark melanoid bands, corky, up to 3 mm thick. Tubes concolorous with pore surface, hard corky, up to 5 mm long.

Hyphal system trimitic, generative hyphae with clamp connections; all the hyphae IKI–, CB–; tissues darkening in KOH. Context composed of generative hyphae colorless, thin-walled, 3–4 Μm in diam.; skeletal hyphae dominant, colorless, thick-walled with a wide to narrow lumen, arboriform, 3–6 Μm in diam.; binding hyphae colorless, branched, flexuous, 1–2 Μm in diam. Tubes composed of generative hyphae scanty; skeletal hyphae dominant, colorless, thick-walled with wide to narrow lumen or solid, occasionally arboriform branched, 3–4.5 μm in diam.; binding hyphae colorless, thick-walled with a narrow lumen, frequently branched, flexuous, 0.8–2 Μm in diam. Pileipellis composed of regular long cylindrical cell, occasionally with dendritic outgrowths and protuberances in the apical or lateral parts, 30–80 × 6–10 Μm. Basidia short 20–24 × 13–15 Μm, clavate, with four sterigmata, colorless, thin-walled; basidioles in shape similar to basidia, but slightly smaller. Basidiospores subglobose to globose, pale yellow brown, IKI–, CB–, doubled-walled, exospore smooth, endospore with conspicuous echinule, (7.5–)8–9.2(–9.5) × (7–)7.2–8(–8.5) Μm, L = 8.66 Μm, W = 7.6 Μm, Q = 1.13–1.15 (n=60/2).

Additional specimens examined:— CHINA. Sichuan Prov.: Mianning County, Lingshansi Park, on ground of angiosperm forest, 13 September 2015, Cui 12646 (paratype, BJFC!), Cui 12647 (paratype, BJFC!) & Cui 12648 (paratype, BJFC!).

Figures

FIGURE 3. Basidiomata and microscopic structures of Amauroderma concentricum (Holotype). a—Basidiomata. b—Apical cells from the cutis. c—Basidia. d—Basidioles. e—Skeletal and binging hyphae from tubes. f—Basidiospores. g—Generative hyphae from context. h—Skeletal and binding hyphae from context. Scale bars: a = 5 cm; b = 20 Μm; c–e = 10 Μm; f–h = 5 Μm. Photos by Xiao-Lan He & Jie Song.