Thelephora griseoumbrina (Litsch. apud Lund. & Nannf.) Kõljalg, I. Saar & Svantesson 2024

Syn.: Tomentella griseoumbrina Litsch. apud Lund. & Nannf. 1936

Basidiome effused, loosely adherent, soft membranaceous, up to 0.2 (0.3) mm thick.
Hymenophore when fresh smooth to shallowly colliculose, light greyish, light greyish brown, light yellowish brown (10YR 6/2–4), when dry tufted to slightly granulose, finely discontinuous, becoming continuous when well developed, uniformly greyish brown to brown or yellowish brown (10YR 5/2–4).
Subhymenium thin to slightly thickening in granules and slightly colliculose parts.
Subiculum soft, loose, araneose to hypochnoid, brown to dark brown (10YR 4–3/3–4), faintly to distinctly darker than the hymenial surface.
Margin indistinct, normally fertile throughout, indefinitely thinning out, pruinose, concolour with the fertile area or infrequently slightly darker and concolour with the subiculum.
Rhizomorphs absent.

Hyphal system monomitic; all hyphae with fibulate primary septa.
Subicular hyphae somewhat irregular, sinuous, short-celled, few next to the substrate more regular and with relatively distant septa, (2.5) 3–4.5 (5) µm wide, normally branching from clamps, sometimes with simple anastomoses and closely spaced clamps, with thickening to thick wall (0.5–1 µm), ochraceous to brownish.
Subhymenial hyphae regular, short-celled, (2) 2.5–4 (5) µm diam., richly branched, with thin to slightly thickening wall, branching from clamps, subhyaline to pale yellowish brown.
Cystidia absent.
Basidia narrowly clavate to subcylindrical, often with a faint median constriction, (15) 18–30 (35) x 3.5–5 µm, hyaline to pale yellowish brown; 4 sterigmata up to 3 (4) µm long and about 1 µm at the base.
Basidiospores with regular outline; frontal face subglobose to broadly ellipsoid or broadly ovoid; lateral face subglobose to broadly ellipsoid with a convex or rarely slightly flattening adaxial side; polar face globose, 4–5.5 µm across or, more precisely, 4.5–5.5 (6) x 4–5 x 4–5.2 (5.5) µm, Q¹ = 1.05–1.25, Q² = 1–1.15, shortly echinulate, with thickening wall (ca. 0.3 µm), light yellowish-brown to ochraceous, mostly 1-guttulate. Aculei up to 0.5 (0.8) µm long, single, sparse, blunt or slightly tapering.Apiculus very small and almost indistinct, less than 0.8 (1) µm long and wide.
Chlamydospores absent.
Incrustation: none.
Chemical reactions: IKI–. CB: inconsistent with all elements more or less cyanophilous or not at all, aculei possibly always cyanophilous. KOH: none or a faint darkening of all elements.

description: Elia Martini

drawing and photo: Elia Martini