Thallus effuse, thin and discontinuous, occasionally thicker (to 400 µm thick), white, non-corticate. Soralia 100-300 µm diam, pale green, covering most of the thallus, soon confluent and appearing effuse; soredia ca 200 µm diam, farinose. Photobiont chlorococcoid, cells 8–12 µm diam.
Anamorph: conidiomata pycnidia, rare; flesh-coloured to pale brown, immersed in thicker areas of the thallus. Conidia 7–8 x 15–20 µm, ellipsoidal to bacilliform.
Teleomorph: ascomata apothecia, 400-800 µm diam, scattered, sessile, becoming tuberculate and then to 1.2 mm diam; disc pinkish brown to pale brown with paler margin, slightly convex, soon becoming tuberculate with excluded margin. Excipulum composed of conglutinate radiating hyphae 5 µm diam; internally colourless to yellow-brown with grey-brown granular intrusions not dissolving in K, outer cells with brown pigment, becoming colourless in K. Hymenium 40–45 µm tall, hyaline, I+ blue, epihymenium brown, granular, becoming colourless in K. Hypothecium hyaline, composed of randomly orientated hyphae. Interascal tissue of paraphyses 1.5–2 µm diam, moderately branched and anastomosing, apices to 3 µm diam, pigmented cap absent. Asci ca 30 x 12 µm, clavate, Bacidia-type. Ascospores (10–)12–15(–20) x 3–4 µm, narrowly ellipsoidal to fusiform, hyaline, 0- or 1-septate, often slightly curved.
Chemistry. Thallus and soredia C--, K+ yellow, Pd+ orange, UV+ dull yellow; atranorin, stictic acid and zeorin by TLC.