Thallus closely to loosely attached, forming regular or irregular, complete or partial rosettes, irregularly encircling twigs, to 12 cm diam., often coalescing to form small colonies, corticolous. Lobes numerous, ± radiating at outer edges, medium, rather uniform, 1.5-2(-3) mm wide, distinct, occasionally discrete at margins, becoming intricately interwoven, zig-zag, markedly contorted centrally and there often copiously secondarily lobulate, terminal lobes ± subdichotomously branched, margins sinuous-angular-convoluted, entire, not, or sparingly blackened, apices concolorous with thallus, hollow, swollen, internal cavity white. Upper surface uneven, mostly convex, occasionally where lobes are bunched, forming ridges, pale greenish-grey, emaculate, ± rugose-uneven, ± matt, perforate, without soredia or isidia. Perforations frequent, mostly median, margins notably elevated, appearing slightly inflated, conical, sometimes with a collar-like rim, 0.5-1.0 mm diam., rounded, oval or crescentic. Apothecia scattered, adnate, 2-10 mm diam., cupuliform at first, margins smooth, crenulate, or with scattered fissures, shining, thinner at maturity, disc 3-7(-10) mm diam., red-brown, shining, epruinose, ± plane to convex, pedicellate, pedicel ± coarsely faveolate. Epithecium red-brown, without granules, c. 10 µm thick. Hymenium colourless, c. 100 µm tall. Paraphyses not thickened at apices. Asci oval, 90-100 × 40-45 µm, 2-spored. Ascospores ellipsoid to subspherical, 48-60 × 32-40 µm [Zahlbruckner, loc. cit. gives 38-50 × 17-22 µm], wall 3-5 µm thick. Chemistry: Atranorin, stictic, constictic and menegazziaic acids and an accessory substance; no pigments; medulla K+ yellow → orange, C-, KC+ orange, Pd+ orange.