Thallus thin, effuse, pale to grey, often tinged greenish or inconspicuous. Isidia and soredia absent. Photobiont Trentepohlia.
Anamorph: conidiomata pycnidia, immersed, punctiform. Conidia 4-6 × 1-1.2 µm, cylindrical, not curved.
Teleomorph: ascomata apothecia, lirellate, 0.5-1.2 × 0.15-0.35 mm, simple, rarely branched, a with dark, well-developed, prominent exciple. Disc at first a slit, ± opening and expanded, not or slightly pruinose. Epithecium olive greenish, K+ green. Hymenium 50-75 µm tall, I–. Ascospores (12-) 14-20 × (3-) 4-5.5 µm, 3- to 5-septate, fusiform, typically with the second of third cell from the apex the most wide, hyaline, fairly thick-walled, smooth, without an epispore, gelatinous sheath or appendages.
Chemistry: thallus C–, K–, KC–, Pd–, UV–. No lichen substances detected by TLC.
Assessed by Woods & Coppins (2012) as of Least Concern. The species is however considered to be Nationally Scarce.
Much confused with Opegrapha varia but differing in the K+ greenish reaction of the epithecium.
Scattered throughout the British Isles with a strong coastal distribution especially in SW England. BLS map here.
On acid-barked trees such as Betula and Taxus, also on dead bramble and fern stems.