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

Index Fungorum number: IF555698; MycoBank number: MB 555698; Facesofungi number: FoF 05622; Figs. 1, 2, 3

Etymology – Refers to the brown and granulose hymenophore of the basidiocarps.

Holotype – IFP 019283.

Basidiocarps annual, resupinate, adherent to the substrate, pelliculose, without odour or taste when fresh, 0.4–0.7 mm thick, continuous. Hymenophoral surface smooth or granulose, brown (7E6–8) when dry. Sterile margin often indeterminate, byssoid, concorlorous with subiculum. Subiculum paler than hymenophore, mostly pale brown. Rhizomorphs present in subiculum and margins, 20–50 μm diam; rhizomorphic surface more or less smooth; hyphae in rhizomorphs monomitic, undifferentiated, of type B, compactly arranged and of uniform; single hyphae clamped, thick-walled, unbranched, 1–1.5 μm diam, greyish yellow in KOH, cyanophilous, inamyloid. Subicular hyphae monomitic; generative hyphae with both clamps and simple septa, thin- to slightly thick-walled, rarely branched, 2–3.5 μm diam, occasionally collapsed and encrusted, greyish yellow in KOH, acyanophilous, inamyloid. Subhymenial hyphae clamped, thin-walled, frequently branched, 2.5–3.5 μm diam; hyphal cells more or less uniform, greyish yellow in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 30–60 μm long and 5–10 μm diam at apex, 4–6 μm at base, with a clamp connection at base, clavate, stalked, sinuous, without transverse septa, pale orange in KOH, yellowish brown in distilled water, 4-sterigmate; sterigmata 1.5–3 μm long and 1–2 μm diam at base. Basidiospores thick-walled, (5–)5.5–8(–8.5)×(4.5–)5–6.8(–7) μm, L=6.55 μm, W=6.02 μm, Q=1.08–1.13 (n=60/2), irregularly globose or lobed in frontal view and ellipsoid in lateral view, echinulate, reddish brown in KOH, reddish golden 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 rotten angiosperm branch, 22 October 2015, Yuan 10725 (IFP 019283, holotype), Yuan 10733 (IFP 019284).

GenBank numbers – ITS: KY686233, KY686232; LSU: MK446371, MK446370.

Notes – Tomentella subvinosa (Burt) Bourdot & Galzin is similar to T. fuscogranulosa by having basidiocarps adherent to the substrate with a smooth or granulose hymenophore, indeterminate sterile margins, the presence of rhizomorphs, thin-walled subhymenial hyphae and irregularly globose or lobed basidiospores. However, the former species is differentiated by vinaceous brown, usually discontinuous basidiocarps, the absence of simple septa in generative hyphae, subicular hyphae without encrustation and smaller basidiospores (6–8 μm, Bourdot and Galzin 1924). T. griseoviolacea Litsch. is similar to T. fuscogranulosa by having continuous basidiocarps with a byssoid sterile margin, a smooth or granulose hymenophore, the presence of rhizomorphs, encrusted subicular hyphae, and irregularly globose or lobed, echinulate spores. However, T. griseoviolacea has greyish brown to blackish brown and arachnoid basidiocarps, generative hyphae lacking of simple septa and smaller basidiospores (5.5–8 μm, Larsen 1974).

Figure 1 – A basidiocarp of Tomentella fuscogranulosa (IFP 019283, holotype)

Figure 2 –SEM of basidiospores of Tomentella fuscogranulosa (IFP 019283, holotype)

Figure 3 – Microscopic structures of Tomentella fuscogranulosa (IFP 019283, holotype). a Hyphae from a rhizomorph. b Section through a basidiocarp. c Basidiospores in frontal view. d Basidiospores in lateral view