Tomentella fuscoaraneosa Y.H. Mu &H.S. Yuan, sp. nov.
Index Fungorum number: IF 900079; MycoBank number: MB 900079; Facesoffungi number: FoF 13399; Figs. 1, 2, 3
Etymology – Refers to the brown and arachnoid basidiocarps.
Holotype – IFP019493
Basidiocarps annual, resupinate, separable to the substrate, arachnoid, without odour or taste when fresh, 0.8–1.5 mm thick, continuous. Hymenophoral surface smooth, light brown to brown (7D8–7E8) and concolorous with subiculum when dry. Sterile margin often determinate, byssoid, concolorous with hymenophore. Rhizomorphs present in subiculum and margin, 10–35 μm diam; rhizomorphic surface more or less smooth; hyphae in rhizomorphmonomitic, undifferentiated, of type B, compactly arranged and of uniform; single hyphae with both clamps and simple septa, thick-walled, unbranched 2–3 μm diam, yellow in KOH, cyanophilous, inamyloid. Subicular hyphae monomitic; generative hyphaeclamped and rarely simple septate, thin- to slightly thick-walled, frequently branched, 2–3 μm diam, withoutencrustation, yellow in KOH, cyanophilous in sightly thick-walled hyphae, inamyloid. Subhymenial hyphae clamped and rarely simple septate, thin-walled, occasionally branched, 2.5–4 μm diam, without encrustation; hyphal cells short and not inflated, yellow in KOH, acyanophilous, inamyloid. Cystidia absent. Basidia 10–65 μm long and 4–7 μm diam at apex, 2–4 μm at the base, with a clamp connection or simple septate at the base, utriform, thin-walled, stalked, sinuous, occasionally with transverse septa, yellow in KOH, yellow in distilled water, 4-sterigmate; sterigmata 2–5 μm long and 1–2 μm diam at the base. Basidiospores thick-walled, (5–)5.5–7.5(–8)×(4–)4.5–6(–7) μm, L=6.29 μm, W=5.32 μm, Q=1.12–1.18 (n=60/2), subglobose to ellipsoid in frontal view and subglobose to ellipsoid in lateral view, echinulateto aculeolate, yellow in KOH, yellow in distilled water, cyanophilous, inamyloid; echinuli usually isolated, sometimes grouped in 2 or more, up to 1.5 μm long.
Material examined – China, Zhejiang Province, Kaihua County, Gutianshan National Nature Reserve, on fallen angiosperm branch, 25 July 2018, Yuan 12875(IFP 019493, holotype); on fallen angiosperm branch, 25 July2018, Yuan 12910 (IFP 019494, paratype).
GenBank numbers – IFP 019493-MZ329769 (ITS), MZ329773 (LSU). IFP 019493-MZ329770 (ITS), MZ329774 (LSU)
Notes – Tomentella fuscoaraneosa is closely related to T. aureomarginata in the phylogeny (Fig. 4). In morphology, T. fuscoaraneosa is similar to T. aureomarginata in having a determinate and byssoid sterile margin, the presence of type B rhizomorphs, monomitic generative hyphae with clamps and simple septa, and the absence of cystidia. However, T. aureomarginata differs from T. fuscoaraneosa by having pelliculose basidiocarps adherent to the substrate, golden brown to yellowish-brown hymenophoral surface turning darker when dry, not stalked basidia and wider basidiospores (6–6.5 μm vs. 4.5–6 μm in T. fuscoaraneosa) with shorter echinuli (up to 1 μm vs. up to 1.5 μm in T. fuscoaraneosa) (Yuan et al. 2020). Tomentella fuscoaraneosa shares common features with T. brunneoflava in arachnoid and continuous basidiocarps, the presenceof rhizomorphs and clamped and rarely simple septate subicular hyphae and short and not inflated subhymenial hyphae. However, T. brunneoflava differs from T. fuscoaraneosa by having brownish-yellow basidiocarps adherent to the substrate and clavate and not stalked basidia (Yuan et al. 2020).
Figure 1 – A basidiocarp of Tomentella fuscoaraneosa (IFP 019493, holotype). Scale bars=0.25 cm
Figure 2 – SEM of basidiospores of Tomentella fuscoaraneosa (IFP 019493, holotype)
Figure 3 – Microscopic structures of Tomentella fuscoaraneosa (IFP 019493, holotype). a Hyphae from a rhizomorph. b Section through a basidiocarp. c Basidiospores in frontal view. d Basidiospores in lateral view
Figure 4 – Phylogram generated from maximum likelihood analysis-based on combined ITS and LSU sequence data. Related sequences were obtained from GenBank and Unite. One hundred and ten strains are included in the combined sequence analyses, which comprise 1451 characters withgaps. Single gene analyses were also performed and topology andclade stability compared from combinbed gene analyses. Odontia ferruginea (TU110988) is used as the outgroup taxon. Bootstrap support values for ML≥50% are given. The newly generated sequences are in bold