Distribution: N - Frl (Tretiach 2004), VA (Isocrono & al. 2008, Favero-Longo & Piervittori 2009).
Description: Thallus crustose, episubstratic, continuous to finely rimose, glaucescent white to greenish grey, sometimes yellowish brown or reddish brown when on iron-rich rocks. Apothecia micareoid, brownish, lead-grey or black, 0.2-0.4 mm across, often confluent into tuberculate, up to 0.8 mm wide aggregates, with a convex to globose disc, from the beginning without a proper margin. Proper exciple absent; epithecium colourless, very pale brown or deep green, K-, N-, or (when green) N+ red; hymenium colourless, pale brown or blue-green, often with vertical pigmented streaks, 30-40 µm high; paraphyses scarce, of two types: the majority sparingly branched and 0.5-1.5 μm thick, the others simple, often fasciculate, and 1.5-2 μm thick; hypothecium dark red-brown , K- or K+ intensifying red, N-. 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, hyaline, ellipsoid, 6-9 x 2-3(-4) µm. Pycnidia black, immersed, inconspicuous, the outer wall reddish brown, K-. Conidia cylindrical, not constricted in the middle, 3.8-5.5 x 0.9-1.4 µm. Photobiont chlorococcoid, the cells thin-walled, 5-15 μm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on siliceous, often metal-rich rocks in dry and sheltered underhangs, in humid natural habitats.