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

Index Fungorum number: IF555744; MycoBank number: Facesofungi number: FoF 05626; Figs. 1, 2, 3

Etymology –  Refers to the greyish brown hymenophoral surface of the basidiocarps.

Holotype –  IFP 019291.

Basidiocarps annual, resupinate, adherent to the substrate, mucedinoid, without odour or taste when fresh, 0.5–0.8 mm thick, continuous. Hymenophoral surface granulose, greyish brown to dark blond (5D3–5D4) and concolorous with subiculum when dry. Sterile margin often indeterminate, farinaceous, concolorous with hymenophore. Rhizomorphs absent. Subicular hyphae monomitic; generative hyphae clamped and simple septate, thick-walled, rarely branched, 3–5 μm diam, without encrustation, some subicular hyphal cells short, pale brown in KOH, cyanophilous, inamyloid. Subhymenial hyphae clamped and simple septate, thin- to slightly thick-walled, rarely branched, 4–6 μm diam; hyphal cells short and inflated, pale brown in KOH, cyanophilous, inamyloid. Cystidia absent. Basidia 15–35 μm long and 4–7 μm diam at apex, 3–5 μm at base, with a clamp connection at base, clavate, not stalked, sinuous, rarely with transverse septa, pale brown in KOH and in distilled water, 4-sterigmate; sterigmata 3–5 μm long and 1.5–2 μm diam at base. Basidiospores slighty thick-walled, (5–)5.5–6.5(–7)×(4–)5–5.5(–6) μm, L=5.92 μm, W=5.06 μm, Q = 1.12–1.21 (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, 9 August 2016, Yuan 11409 (IFP 019291, holotype), Yuan 11401 (IFP 019292).

GenBank numbers –  ITS: MK211719, MK211718; LSU: MK446379, MK446378.

Notes –  Tomentella coerulea Höhn. & Litsch. resembles T. griseocastanea by having greyish brown and continuous basidiocarps adherent to the substrate with a granulose hymenophoral surface, a farinaceous sterile margin, the absence of cystidia, and subglobose to bi-, tri- or quadralobed basidiospores. However, T. coerulea is differentiated by a whitish sterile margin, thin-walled subicular hyphae and the presence of rhizomorphs (Kõljalg 1996; Daemmrich 2006; Melo et al. 2006). T. subclavigera Litsch., T. clavigera Litsch. and T. griseocastanea also share continuous basidiocarps adherent to the substrate, short subhymenial hyphal cells and the absence of rhizomorphs. However, T. subclavigera and T. clavigera differ from T. griseocastanea by having thin-walled subicular hyphae and clavate cystidia (Kõljalg 1996; Melo et al. 1998; Daemmrich 2006).

Figure 1 – A basidiocarp of Tomentella griseocastanea (IFP 019291, holotype)

Figure 2 – SEM of basidiospores of Tomentella griseocastanea (IFP 019291, holotype)

Figure 3 – Microscopic structures of Tomentella griseocastanea (IFP 019291, holotype). a Section through a basidiocarp. b Basidiospores in frontal and lateral views