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

Index Fungorum number: IF 555630; MycoBank number: MB 555630; Facesoffungi number: FoF 05605; Figs. 1, 2, 3

Etymology: Refers to the short sterigmata of the basidia.

Holotype: IFP 019249.

Basidiocarps annual, resupinate, adherent to the substrate, mucedinoid, without odour or taste when fresh, 0.5–1 mm thick, discontinuous. Hymenophoral surface granulose, brownish beige to greyish brown (6E3–6F3) and concolorous with subiculum when dry. Sterile margin often determinate, farinaceous, concolorous with hymenophore. Rhizomorphs present in subiculum and margins, 25–40 μm diam; rhizomorphic surface more or less smooth; hyphae in rhizomorph monomitic, differentiated, of type C; central hyphae with both clamps and simple septa, somewhat enlarged, thickwalled, unbranched, 3–4 μm diam; hyphae outer part of rhizomorphs with both clamps and simple septa, slightly thickwalled, unbranched, 2–2.5 μm diam; pale-brown in KOH, acyanophilous, inamyloid. Subicular hyphae monomitic; generative hyphae clamped, thick-walled, occasionally branched, 3–5 μm diam, without encrustation, pale brown in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped, thin- to slightly thick-walled, rarely branched, 3–6 μm diam; hyphal cells short and inflated, pale brown in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 10–30 μm long and 3–5.5 μm diam at apex, 2.5–3 μm at base, with clamp connection at base, clavate, not stalked, sinuous, pale brown in KOH and in distilled water, 4-sterigmate; sterigmata 2–3.5 μm and 1–1.5 μm diam at base. Basidiospores slightly thick-walled, (4.5–)5–6.5(–7)×(4–) 4.5–5.5(–6) μm, L=5.93 μm, W=4.83 μm, Q=1.17–1.23 (n=60/2), subglobose to bi-, tri- or quadra-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 μm long.

Material examined: CHINA, Jilin Province, Changbaishan Nature Reserve, on fallen angiosperm branch, 7 August 2016, Yuan 11328 (IFP 019249, holotype); on rotten angiosperm stump, 7 August 2016, Yuan 11332 (IFP 019250).

GenBank numbers: ITS: MK211746, MK211747; LSU: MK446340, MK878396.

Notes: The fuscous black, mouse grey or greyish sepia, continuous basidiocarps of Tomentella botryoides are similar to T. brevis. In addition, they also share some other characteristics: clamped hyphae, clavate basidia, the presence of rhizomorphs and the absence of cystidia. However, T. botryoides differs from T. brevis by having pelliculose basidiocarps separable from the substrate, a byssoid sterile margin and subglobose to bi-, tri-lobed basidiospores (Kõljalg 1996; Daemmrich 2006). T. lateritia Pat. resembles T. brevis by having continuous basidiocarps adherent to the substrate, clamped hyphae, clavate basidia and the absence of cystidia. But, the former species is differentiated by brick or umber basidiocarps with a granulose hymenophoral surface, subglobose to bi-lobed basidiospores and the absence of rhizomorphs (Kõljalg 1996; Daemmrich 2006; Melo et al. 2006).

Figure 1 – A basidiocarp of Tomentella brevis (IFP 019249, holotype)

Figure 2 – SEM of basidiospores of Tomentella brevis (IFP 019249, holotype)

Figure 3 – Microscopic structures of Tomentella brevis (IFP 019249, holotype). a Hyphae from a rhizomorph. b Section through a basidiocarp. c Basidiospores in frontal view. d Basidiospores in lateral view