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

Index Fungorum number: IF 555697; MycoBank number: MB 555697; Facesoffungi number: FoF 05619; Figs. 1, 2, 3

Etymology – Refers to the yellowish brown basidiocarps.

Holotype – IFP 019277.

Basidiocarps annual, resupinate, separable from the substrate, mucedinoid, without odour or taste when fresh, 0.2–0.25 mm thick, continuous. Hymenophoral surface smooth, yellowish brown (5D8) and concolorous with subiculum when dry. Sterile margin often indeterminate, byssoid, paler than hymenophore, pale brown (6D7). Rhizomorphs present in subiculum, 10–20 μm diam; rhizomorphic surface more or less smooth; hyphae in rhizomorphs monomitic, undifferentiated, of type B, compactly arranged and of uniform; single hyphae clamped, thin- to slightly thick-walled, unbranched, 1–2 μm diam, golden yellow in KOH, cyanophilous, inamyloid. Subicular hyphae monomitic; generative hyphae clamped, thin- to slightly thick-walled, occasionally branched, 3–4 μm diam, occasionally collapsed, without encrustation, yellow in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped, thin-walled, frequently branched, 3–4.5 μm diam; hyphal cells more or less uniform, golden yellow in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 30–50 μm long and 6–9 μm diam at apex, 3–5 μm at base, with a clamp connection at base, clavate, stalked, not sinuous, rarely with transverse septa, golden yellow in KOH, deep yellow in distilled water, 4-sterigmate; sterigmata 3–5 μm long and 1.5–2.5 μm diam at base. Basidiospores thick-walled, (6.5–)6.7–9(–9.5)×(4.5–)5–7.9(–8.5) μm, L=7.72 μm, W=5.68 μm, Q=1.22–1.41 (n=60/2), subglobose to bi-, tri- or quadra-lobed in frontal view and ellipsoid in lateral view, echinulate, oxide yellow in KOH, deep yellow in distilled water, cyanophilous, inamyloid; echinuli usually grouped in 2 or more, up to 1 μm long. Material examined: CHINA, Liaoning Province, Kuandian County, Baishilazi Nature Reserve, on fallen angiosperm branch, 1 August 2016, Yuan 11044 (IFP 019277, holotype), Yuan 11061 (IFP 019278).

GenBank numbers – ITS: KY686231, KY686230; LSU: MK446364, MK446365.

Notes – Tomentella kentuckiensis M.J. Larsen is similar to T. flavidobadia by having mucedinoid, continuous basidiocarps, a smooth hymenophore, the presence of rhizomorphs, clamped and thin-walled subhymenial hyphae and irregular globose or lobed basidiospores. However, the former species
is differentiated by paler coloured basidiocarps adherent to the substrate and bigger basidiospores (8–11 μm, Larsen 1974). T. longiaculeifera resembles T. flavidobadia by having mucedinoid, yellowish brown basidiocarps, a smooth hymenophoral surface and approximately the same-sized basidiospores. However, T. longiaculeifera lacks rhizomorphs and has thick-walled subhymenial hyphae.

Figure 1 – A basidiocarp of Tomentella flavidobadia (IFP 019277, holotype)

Figure 2 – SEM of basidiospores of Tomentella favidobadia (IFP 019277, holotype)

Figure 3 – Microscopic structures of Tomentella flavidobadia (IFP 019277, holotype). a Hyphae from a rhizomorph. b Section through a basidiocarp. c Basidiospores in frontal view. d Basidiospores in lateral view