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

Index Fungorum number: IF 555750; MycoBank number: MB 555750; Facesofungi number: FoF 05634; Figs. 1, 2, 3

Etymology – Refers to the long echinuli on the basidiospores.

Holotype – IFP 019305.

Basidiocarps annual, resupinate, adherent to the substrate, pelliculose, without odour or taste when fresh, 1–1.5 mm thick, continuous. Hymenophoral surface smooth, pale brown to brown (6D4–6E5) and slightly lighter than subiculum when dry. Sterile margin often indeterminate, farinaceous, concolorous with hymenophore. Rhizomorphs absent. Subicular hyphae monomitic; generative hyphae clamped, thick-walled, occasionally branched, 4–9 μm diam, without encrustation, pale brown in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped, thin-walled, occasionally branched, 4–7 μm diam; hyphal cells short and not inflated, pale brown in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 10–50 μm long and 6–13 μm diam at apex, 5–9 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 3–8 μm long and 2–3 μm diam at base. Basidiospores thick-walled, (8–)8.5–10.5(–12)×(7–)7.5–9(–10) μm, L=9.37 μm, W=8.47 μm, Q=1.08–1.25 (n=60/2), subglobose to bi-lobed in frontal and lateral views, echinulate, pale brown in KOH and in distilled water, cyanophilous, inamyloid; echinuli usually isolated, up to 3 μm long.

Material examined – CHINA, Heilongjiang Province, Fenglin National Nature Reserve, on fallen angiosperm branch, 16 October 2016, Yuan 11979 (IFP 019305, holotype), Yuan 12083 (IFP 019306).

GenBank numbers – ITS: MK211726, MK211727; LSU: MK446393, MK446394.

Notes – Tomentella griseofusca is similar to T. longiechinuli by the brownish basidiocarps, clamped hyphae, short subhymenial hyphal cells, utriform basidia and the absence of rhizomorphs and cystidia. However, the former species
is differentiated by crustose basidiocarps, thick-walled subhymenial hyphae and globose to subglobose basidiospores. T. conclusa resembles T. longiechinuli by the basidiocarps adherent to the substrate, short subhymenial hyphal cells, utriform basidia and the absence of rhizomorphs and cystidia. However, T. conclusa differs from T. longiechinuli by the inflated subhymenial hyphal cells and globose to subglobose basidiospores with shorter echinuli (echinuli up to 2.5 μm long).

Figure 1 – A basidiocarp of Tomentella longiechinuli (IFP 019305, holotype)

Figure 2 – SEM of basidiospores of Tomentella longiechinuli (IFP 019305, holotype)

Figure 3 – Microscopic structures of Tomentella longiechinuli (IFP 019305, holotype). a Section through a basidiocarp. b Basidiospores in frontal view. c Basidiospores in lateral view