Thelephora giacomoi Kõljalg, I. Saar & Svantesson 2024

Syn.:Tomentella bresadolae (Brinkmann) Bourdot & Galzin 1908

Basidiome effused, when fresh separable, at least in small pieces, flocked to soft membranaceous, tomentose or slightly felted, when dry adherent and mostly detaching in small incoherent or tufted granules, up to 0.3 (0.5) mm thick.
Hymenophore smooth, mostly finely discontinuous to very finely porulose and irregular at 10X, rarely almost continuous, when fresh brown to dark brown with a light greyish or purplish tint (7.5–10YR 4–3/2–3), when dry brown to dark brown (10YR 4–3/3–4).
Subhymenium not compact, slightly thickening, up to 0.1 (0.2) mm thick.
Subiculum arachnoid to tomentose, up to 0.2 (0.3) mm thick, brown to dark brown (10YR 4–3/3), when fresh more or less differently coloured than the fertile surface, when dry almost concolour.
Margin indefinitely thinning out, fibrillose and discolour (whitish) in fresh and actively growing specimens, otherwise indistinct, almost fertile throughout, porulose, discontinuous.

Hyphal system monomitic; hyphae with mostly fibulate primary septa; simple septa rarely found.
Subicular hyphae regular, frequently branched and arranged in all directions, distinct, (4.5) 5–6.5 (7) µm wide, with thickening to thick wall (0.5–1 µm), often with localized thickenings, branching at some distance from septa, yellowish brown to brown or umbrinous; few basal hyphae running more or less parallel to the substratum, with longer cells, infrequently branched and rarely with thick walls (1.5–2 µm) and some repetitive secondary septa.
Subhymenial hyphae short-celled, mostly irregular, 4–10 µm wide, sometimes becoming triangular or botryose in deep subhymenium near the subiculum and then widened up to 20 µm, with thin to thickening wall (0.5 µm), often branched from clamps, subhyaline to distinctly pigmented some shade of brown.
Rhizomorphs absent.
Cystidia absent.
Basidia when immature often somewhat obpyriform, then subcylindrical to utriform, often stout, 40–65 (75) x (10) 11–13 (15) µm at top, (8) 10–14 µm in the lower middle, almost thin-walled, subhyaline to pale brown, often guttulate; (2) 4 sterigmata 10–14 (15) µm long and (2.5) 3–4 µm wide at the base.
Basidiospores with regular outline, frontal face subglobose to broadly ellipsoid or broadly ovoid, lateral face broadly ellipsoid to subglobose with slightly flattening adaxial side, polar face globose, 10–13 µm across or, more precisely, (9.5) 10–13 (13.5) x 8.5–11.2 (11.5) x 9.5–12.5 (13) µm, Q¹ = 1.1-1.3, Q² = 0.9-1.15, aculeate, yellowish brown to brown, normally with a large drop, wall about 1 µm thick. Aculei single, tapering, 2–3 (3.5) µm long and 0.5–1.2 (1.5) µm wide at the base. Macrospores infrequent 14–16 µm across.
Chlamydospores absent.
Incrustation: none.
Chemical reactions: IKI: often localized thickenings becoming bluish or bluish grey, all other elements non amyloid. CB: inconsistent, some young spores and thin-walled hyphae cyanophilous, thick-walled elements acyanophilous but sometimes thin wall layers seemingly cyanophilous (hyphae and aculei). KOH: a slight darkening of all elements that loose some yellow hue.

description: Elia Martini

drawings and photo:: Elia Martini