Thelephora aurantiobrunnea Kõljalg, I. Saar & Svantesson 2024

Syn.: Tomentella rubiginosa (Bres.) Maire 1906

Basidiome effused, separable, araneose to byssoid in immature parts, hypochnoid, tomentose, soft membranaceous or somewhat crustose and brittle when old; up to 0.2 (0.3) mm thick.

Hymenophore at first discontinuous, porulose, tufted, then granulose, rarely with smooth or colliculose parts, yellow-orange (5–7.5YR 6–4/8–12) when young, then orange brown to ferrugineous brown (5–10YR 4–3/4-8), rarely assuming a faint olivaceous hue (10YR–2.5Y 5–4/4).

Subiculum scanty to rather well developed, loose, araneose to byssoid, soft, yellowish-orange to yellowish brown (5–10YR 7–6/8), sometimes becoming strong brown (7.5YR 5/6–8), or even dark brown, depending on the presence, abundance and colour of rhizomorphs.

Margin shortly thinning out, fertile and concolour to almost sterile and byssoid to fimbriate and then paler, yellowish to yellow-orange.

Rhizomorphs common in subiculum, at the margin and in cracks of the substratum, up to 0.05 (0.1) mm thick, often branched in all directions, sometimes arranged in ropes, compact, becoming hard and rigid, with almost smooth surface, yellowish brown to dark brown.

Hyphal system dimitic with short skeletoid hyphae associated with rhizomorphs.

Subicular hyphae regular, fibulate, sometimes with intercalary simple septa, (2.5) 3–4 (5) µm wide, sometimes with simple anastomoses, with thin to thickening wall, yellow to golden yellow or yellow-orange, normally branching at some distance from septa.

Subhymenial hyphae regular, fibulate, (2) 2.5–4 µm wide, thin-walled, subhyaline, yellowish to golden yellow, often branching from clamps.

Rhizomorphs starting as rather loose strands of fibulate generative hyphae in subiculum, soon mixed with some 2–3 µm wide, sinuos and sparsely branched hyphae with thickening walls and frequent simple or adventitious septa that end with strongly branching thin hyphae 0.5–1.5 µm wide with thin walls and frequent simple septa. Old rhizomorphs with slightly wider hyphae (up to 6 µm) in the core surrounded by some, relatively short, hyphae 2–3 µm in diam. as described above that forms a discontinuous compact labyrinthiform layer on the surface.

Cystidia absent.

Basidia narrowly clavate, sinuos, (35) 45–60 (80) x 6–9 (10) µm, fibulate at the basal septum, subhyaline to pale yellowish, often with homogeneous yellow-ochre content or guttulae; 4 sterigmata up to 6 (8) µm long and 1–2 µm wide at the base.

Basidiospores mostly with irregular outline, frontal somewhat three-lobed, lateral face with regular to sinuous outline, ellipsoid with flattening adaxial side to two-lobed and broader toward the base, polar view subglobose to transversally subglobose, sometimes with sinuous outline and rarely more or less three-lobed, (6.5) 7–8 (8.5) x (5) 5.5–6.5 (7) x 6.5–7.5 (8) µm, Q1 1.1–1.4 (1.5), Q2 = 0.95–1.15 (1.2), echinulate, yellowish to yellowish brown; aculei up to 1.5 (2) µm long, tapering, not or rarely disposed in crowns; apiculus prominent.

Incrustation: a lot of adhering yellowish, ochraceous to reddish brown resinous matter on basidia and subhymenial hyphae visible in water and LA, almost completely dissolving in KOH and producing a yellowish diffusate.

Description: E. Martini

Drawings and Photo: Elia Martini