Thallus rosette-forming or ± irregular, individual rosettes small to medium, seldom exceeding 5 cm diam., but often coalescing with adjoining thalli to cover larger areas of substrate, closely attached, corticolous. Lobes very numerous, small, delicate and fragile, 0.5-0.8 mm wide, to 5 mm long but usually much shorter, irregularly branched, sometimes appearing palmate towards margins, mostly closely contiguous throughout entire length, often imbricate centrally, margins sinuous, entire or notched, hollow, lower side of internal cavity blackened, apices ± elevated, ± pale brown or red-brown. Upper surface concave or plane, shining, pale green-grey or green with faint, white, irregular, incomplete reticulate maculae (× 10 lens) best seen on marginal lobes, margins not, or only slightly blackened. Perforations absent from both upper and lower surfaces, soredia absent, isidiate. Isidia often very numerous and sometimes completely obscuring older parts of thallus, rather coarse, 0.15-0.25 mm diam., and 0.5-1.3 mm tall, simple at first becoming branched, terete to spathulate or flattened and then occasionally dorsiventral with pale brown underside, often decumbent on thallus, very fragile and easily abraded, arising as papillate outgrowths of upper surface, rarely marginal, concolorous with thallus, apices pale brown to red-brown. Apothecia not seen. Chemistry: Atranorin (cortex), stictic, constictic, norstictic (tr.) and menegazziaic acids and other accessory substances, medulla K+ orange, C-, KC+ orange, Pd+ orange.