Thallus pale olive-green, thin, smooth, glossy. Ascomata numerous, scattered, sessile, greyish black, with a conspicuous thalline margin, curved or sinuous, occasionally branched, 1–7 mm long, 0.7–0.9 (–1.0) mm wide. Proper exciple laterally carbonised, hidden by the thalline margin, red-brown at the base. Hymenium 200–250 µm thick. Ascospores 1 per ascus, pale brown, muriform, c. 20 × 5–6-locular, 160–200 × 30–40 µm.
CHEMISTRY: Echinocarpic acid (major), 4-O-methylechinocarpic acid [conechinocarpic acid] (minor).