Tomentella atrobadia H.S. Yuan & Y.C. Dai, sp. nov.

Index Fungorum number: IF 555627; MycoBank number: MB 555627; Facesoffungi number: FoF 05602; Figs. 115, 116, 117

Etymology: Refers to the dark brown basidiocarps.

Holotype: IFP 019243.

Basidiocarps annual, resupinate, adherent to the substrate, crustose, without odour or taste when fresh, 0.5–0.8 mm thick, continuous. Hymenophoral surface smooth, dark brown (6F5–7F5) and paler than subiculum when dry. Sterile margin often indeterminate, byssoid, concolorous with hymenophore. Subiculum mostly dark brown. Rhizomorphs absent. Subicular hyphae monomitic, generative hyphae clamped, thick-walled, rarely branched, 6–7 μm diam, without encrustation, yellow in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped, thick-walled, frequently branched, 6–8 μm diam; hyphal cells short and inflated, yellow in KOH, cyanophilous, inamyloid. Cystidia absent. Basidia 40–60 μm long and 8–15 μm diam at apex, 5–8 μm  at base, with a clamp connection at base, utriform, stalked, not sinuous, rarely with transverse septa, yellow in KOH, yellow in distilled water, 4-sterigmate; sterigmata 5–7 μm long and 3–4 μm diam at base. Basidiospores thick-walled, (9–)9.4–10.5(–11)×(7.5–)8–9.9(–10.5) μm in lateral and frontal views, L = 9.87 μm, W = 8.8 μm, Q = 1.07–1.15 (n=60/2), globose, subglobose, triangular or lobed in frontal view and subglobose to ellipsoid in lateral view, echinulate to aculeolate, yellow in KOH, yellow in distilled water, cyanophilous, inamyloid; echinuli usually isolated, sometimes grouped in 2 or more, up to 1.5 μm long.

Material examined: CHINA, Liaoning Province, Xifeng County, Binglashan National Forest Park, on rotten angiosperm branch, 2 August 2016, Yuan 11099 (IFP 019243, holotype); on rotten angiosperm wood debris, 2 August 2016, Yuan 11114 (IFP 019244).

GenBank numbers: ITS: KY686248, KY686249; LSU: MK446335, MK446336.

Notes: Tomentella stuposa (Link) Stalpers is similar to T. atrobadia by having continuous and brown-coloured basidiocarps adherent to the substrate, a smooth hymenophoral surface, thick-walled hyphae, globose basidiospores of approximately the same size and the absence of rhizomorphs. However, T. stuposa is differentiated by having simple septate subicular hyphae, thin-walled subhymenial hyphae and triangular or lobed basidiospores (Kõljalg 1996). T. alpina Peintner & Dämmrich is similar to T. atrobadia by having continuous basidiocarps adherent to the substrate, smooth hymenophore, the absence of rhizomorphs, clamped and thick-walled subicular hyphae and globose or subglobose basidiospores. But, the former species has distinctly smaller basidospores (6.5–8.5 μm diam, Peintner and Dämmrich 2012).

Fig. 115 A basidiocarp of Tomentella atrobadia (IFP 019243, holotype)

Fig. 116 SEM of basidiospores of Tomentella atrobadia (IFP 019243, holotype)

Fig. 117 Microscopic structures of Tomentella atrobadia (IFP 019243, holotype). a Section through a basidiocarp. b Basidiospores in frontal view. c Basidiospores in lateral view