Tomentella fuscocrustosa H.S. Yuan, X. Lu & Y.C. Dai, sp. nov.

Index Fungorum number: IF 555741; MycoBank number: MB 555741; Facesoffungi number: FoF 05620; Figs. 1, 2, 3

Etymology – Refers to the brown and crustose basidiocarps.

Holotype – IFP 019279.

Basidiocarps annual, resupinate, adherent to the substrate, crustose, without odour or taste when fresh, 0.6–1 mm thick, continuous. Hymenophoral surface smooth, pale brown to brown (6D4–6E4) and concolorous with subiculum when dry. Sterile margin often determinate, byssoid, concolorous with hymenophore. Rhizomorphs present in subiculum and margins, 25–40 μm diam; rhizomorphic surface more or less smooth; hyphae in rhizomorphs monomitic, undifferentiated, of type A, loosely interwoven and of uniform; single hyphae clamped, thick-walled, occasionally branched, 3.5–4.5 μm diam, pale brown in KOH, cyanophilous, inamyloid. Subicular hyphae monomitic; generative hyphae clamped and rarely simple septate, thick-walled, occasionally branched, 3.5–6.5 μm diam, without encrustation, pale brown in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped and rarely simple septate, thin- to slightly thick-walled, rarely branched, 4–7 μm diam; hyphal cells short and inflated, pale brown in KOH, cyanophilous, inamyloid. Cystidia absent. Basidia 20–60 μm long and 5–9 μm diam at apex, 1.5–4 μm at base, with a clamp connection at base, clavate, stalked, sinuous, without transverse septa, pale brown in KOH and in distilled water, 4-sterigmate; sterigmata 3–6 μm long and 1.5–2 μm diam at base. Basidiospores slightly thick-walled, (6–)6.5–8.5(–9)×(5–)5.5–6.5(–7) μm, L=7.35 μm, W=6.12 μm, Q=1.17–1.35 (n=60/2), subglobose to bi- or tri-lobed in frontal and lateral views, echinulate, pale brown in KOH and distilled water, cyanophilous, inamyloid; echinuli usually isolated, sometimes grouped in 2 or more, up to 1.2 μm long.

Material examined – CHINA, Jilin Province, Changbaishan Nature Reserve, on fallen angiosperm branch, 9 August 2016, Yuan 11420 (IFP 019279, holotype), Yuan 11399 (IFP 019280).

GenBank numbers – ITS: MK211713, MK211712; LSU: MK446367, MK446366.

Notes – Tomentella ellisii (Sacc.) Jülich & Stalpers is similar to T. fuscocrustosa by having continuous basidiocarps adherent to the substrate with a smooth hymenophoral surface, short and inflated subhymenial hyphae cells, the presence of rhizomorphs, the absence of cystidia, and subglobose to bi- or tri-lobed basidiospores. However, T. ellisii differs in its utriform basidia and thin-walled subicular and subhymenial hyphae (Stalpers 1993; Kõljalg 1996). T. pallidomarginata resembles T. fuscocrustosa by having continuous basidiocarps adherent to the substrate, a smooth hymenophoral surface, short and inflated subhymenial hyphal cells, the presence of rhizomorphs, the absence of cystidia, and subglobose to bi- or tri-lobed basidiospores. However, the former species is differentiated by dark blonde to brown basidiocarps, a pale yellow to champagne sterile margin and utriform basidia.

Figure 1 – A basidiocarp of Tomentella fuscocrustosa (IFP 019279, holotype)

Figure 2 – SEM of basidiospores of Tomentella fuscocrustosa (IFP 019279, holotype)

Figure 3 – Microscopic structures of Tomentella fuscocrustosa (IFP 019279, holotype). a Hyphae from a rhizomorph. b Section through a basidiocarp. c Basidiospores in frontal view. d Basidiospores in lateral view