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

Index Fungorum number: IF 555773; MycoBank number: MB 555773; Facesofungi number: FoF 05643; Figs. 1, 2, 3

Etymology – Refers to the isolated echinuli of the basidiospores.

Holotype – IFP 019323.

Basidiocarps annual, resupinate, adherent to the substrate, mucedinoid, without odour or taste when fresh, 0.8–1.5 mm thick, discontinuous. Hymenophoral surface smooth, pale brown to dark brown (6D8–6F6) and concolorous with subiculum when dry. Sterile margin often indeterminate, farinaceous, concolorous with hymenophore. Rhizomorphs absent. Subicular hyphae monomitic; generative hyphae clamped and rarely simple septate, slightly thick- to thick-walled, frequently branched, 3–5 μm diam, without encrustation, pale brown in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped and rarely simple septate, thin-walled, occasionally branched, 4–6 μm diam; hyphal cells short and inflated, pale brown in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 15–40 μm long and 5–8 μm diam at apex, 4–6 μm at base, with a clamp connection at base, utriform, not stalked, sinuous, without transverse septa, pale brown in KOH and in distilled water, 4-sterigmate; sterigmata 4–7 μm long and 1.5–2 μm diam at base. Basidiospores slightly thick-walled, (7.5–)8–9(–9.5)×(7–) 7.5–8.5(–9) μm, L=8.65 μm, W=7.7 μm, Q =1.08–1.15 (n = 60/2), globose to subglobose in frontal and lateral views, echinulate, pale brown in KOH and distilled water, cyanophilous, inamyloid; echinuli usually isolated, up to 2.5 μm long.

Material examined – CHINA, Liaoning Province, Huanren County, Laotudingzi National Nature Reserve, on fallen angiosperm branch, 20 October 2015, Yuan 11256 (IFP 019323, holotype); Jilin Province, Changbaishan Nature Reserve, on living tree root, 6 August 2016, Yuan 10650 (IFP 019324).

GenBank numbers – ITS: MK211735, MK211734; LSU: MK446412, MK446411.

Notes – Tomentella globospora is similar to T. segregata by the basidiocarps adherent to the substrate, a smooth hymenophoral surface, a farinaceous sterile margin, globose to subglobose basidiospores and the absence of rhizomorphs
and cystidia. However, T. globospora differs from T. segregata by having crustose basidiocarps and more or less uniform subhymenial hyphal cells. T. pertenuis is similar to T. segregata by having basidiocarps adherent to the substrate with a smooth hymenophoral surface and farinaceous sterile margin, utriform basidia, globose to subglobose basidiospores and the absence of rhizomorphs and cystidia. However, T. pertenuis differs from T. segregata by having slightly thick-walled subicular hyphae and more or less uniform subhymenial hyphal cells.

Figure 1 – A basidiocarp of Tomentella segregata (IFP 019323, holotype)

Figure 2 – SEM of basidiospores of Tomentella segregata (IFP 019323, holotype)

Figure 3 – Microscopic structures of Tomentella segregata (IFP 019323, holotype). a Section through a basidiocarp. b Basidiospores in frontal view. c Basidiospores in lateral view