Thallus pale yellowish green, areolate, medulla I–; areoles flat to convex, 300-800 µm diam; prothallus distinct, black, often coating the sides of the areoles.
Anamorph: conidiomata pycnidia, immersed in areoles, black. Conidia 20-29 × 0.5 μm, curved.
Teleomorph: ascomata apothecia, 300-800 µm diam, black, immersed, later convex, with thin, dark brown exciple; epithecium olive brown-green to dark bluish; hypothecium hyaline. Asci Lecanora type. Ascospores 11-15 × 5-7 μm.
Chemistry: Thallus C–, K+ faintly yellow, Pd–, UV+ pink (usnic acid).
The colour of the thallus is distinct, being something between a yellow Rhizocarpon and a Lecanora of the L. polytropa group.
In GB&I, locally frequent on Cambrian quartzite in the NW Highlands, also known from the Cairngorms (Banffshire and E Perthshire) and Ben Lawers, mostly above 800 m alt. Also reported from Europe, Macaronesia and Africa.
On fine-grained acidic rocks, especially granite and quartzite.