Description: Thallus crustose, episubstratic, yellowish brown or greenish white, rimose and sometimes almost areolate, mostly finely granulose. Apothecia micareoid, sessile, not constricted at base, 0.15-0.3 mm across, sometimes confluent and forming up to 0.6 mm wide, tuberculate aggregates, with a convex-hemispherical, black to bluish black disc, from the beginning without a distinct proper margin. Proper exciple absent; epithecium colourless or greenish, K-, N+ red; hymenium greenish, 30-40 μm high; paraphyses scarce, of two types: the majority sparingly branched and 0.5-1.5 μm thick, others simple, often fasciculate, and 1.5-2 μm thick; hypothecium dark green and N+ red in upper part, olive-black in lower part, of interwoven hyphae. Asci 8-spored, cylindrical-clavate, the I+ blue tholus with a wide, I+ dark blue tube structure that expands towards the top, without a pale axial body, Psora-type. Ascospores 1-celled or 1-septate, hyaline, oblong-ovoid or oblong-ellipsoid, thin-walled, 5.5-8(-9) x 1.5-2.5 µm. Pycnidia to 0.2 mm across, immersed, the wall dark green, K-, N+ red. Conidia bacilliform, 3-4.5 x 1.1-4 μm. Photobiont chlorococcoid, thin-walled, the cells globose and 5-12 µm wide, or ellipsoid and up to 15 x 10 µm. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: no lichen substances in thallus.
Note: on siliceous rocks in humid forests, but also on exposed roots, in underhangs.