Description: Thallus crustose, episubstratic, dark reddish brown, areolate, the areoles contiguous, angular, 0.2-0.5 mm wide, the peripheral ones slightly elongate, forming small, subplacodioid, up to 1 cm wide rosettes, without a distinct pro- or hypothallus. In section the thallus is homoiomerous and pseudoparenchymatous throughout, often overlain by a thin epinecral layer, 130-140 mm thick, the hyphae with with more or less isodiametric, 5-8 mm wide cells. Apothecia pycnoascocarps (developing from pycnidia), lecanorine-aspicilioid, 0.1-0.3 mm across, at first punctiform, then with an expanded disc, immersed in the areoles (usually 1 per areole) with a dark reddish brown, sometimes marginally slightly pruinose disc, and a very thin, finally often excluded thalline margin. Proper exciple poorly developed; epithecium pale reddish brown, K/I+ blue; hymenium colourless, 40-50 mm high, K/I+ blue; paraphyses strongly moniliform, branched in upper part, the apical cells not swollen; hypothecium colourless, opaque, 40-45 mm thick. Asci 8-spored, subglobose, unitunicate-rostrate, the wall thick, with a collar like amyloid inner layer. Ascospores 1-celled, hyaline, narrowly ellipsoid, often curved and appearing falcate or allantoid, 8-9 x 3-4 μm. Photobiont chlorococcoid. Spot tests: Thallus K-, C-, KC-, P-, UV-, I+ reddish. Chemistry: without lichen substances.
Note: on steeply inclined surfaces of siliceous rocks with periodical water seepage after rain, both in the Mediterranean Region and in dry-warm Alpine valleys; perhaps overlooked, but certainly not common.