Thallus composed of soredia, soredia farinose, less than 0.1 mm broad, pale yellowish white to yellowish gray, forming a thin or thick crust; algae Chlorococcaceae. Apothecia to 1 mm broad, first immersed in thallus then convex and surficial, black, often contorted; margin black, disappearing; exciple dark blue-green throughout; hypothecium hyaline to pale yellow; epihymenium granular, dark blue-green; hymenium 60-70 μm, containing crystals; paraphyses 1 μm, slightly branched at tips; asci clavate 40-60 x 12-20 μm; spores 8, hyaline, ellipsoid to ovoid, 13-17 x 7-8 μm.

Reactions: soredia C+ orange, K+ yellow, KC+ orange, P—; exciple K+ dull brownish blue; hypothecium and hymenium I—; walls of asci 1+ blue.

Contents: probably xanthones.

This species is found on decaying timber in Britain. Ahti et al. (1973) reported it on dead Picea twigs and driftwood in the Northwest Territories. It is a rare species known only from England, Germany, and Sweden in Europe, and in North America from the reports by Ahti et al. from the Reindeer Preserve in the Northwest Territories. The key by Laundon (1963) is very helpful in distinguishing sterile crustose lichens on barks and wood.