Description: Thallus crustose-placodioid, episubstratic, forming orbicular, up to 1 cm wide rosettes, yellow-orange to orange (yellow in shade-forms), usually abundantly pruinose. Central part of thallus with 0.3-1.3 mm wide, strongly convex, irregular to elongate areoles formed by lobe fragmentation; marginal lobes convex, irregular or finger-like, slightly broadening at tips, with short and often forked terminal branches, 0.1-1(-1.5) mm long, 0.1-0.6(-0.9) mm wide. Upper cortex with a 6-18.5(-22.5) μm thick brownish-orange upper layer, and a hyaline (6-)10-45(-50) μm thick intemal layer of irregularly arranged hyphae; medulla lax. Apothecia common, pseudolecanorine, more or less crowded, 0.13- 0.7(-0.9) mm across, round or slightly deformed by mutual compression, located either on the areoles or on the lobe bases, sessile to constricted at base. Disk flat to strongly convex, concave in young apothecia, reddish-orange to brownish, somewhat pruinose, smooth; margin paler than disk, without differentiation between proper and thalline margin, slightly pruinose, smooth, 25-100 μm. Epithecium 6-12 μm thick, brownish-orange K+ red; hymenium, subhymenium and hypothecium colourless; paraphyses distinctly septate, forked or subapically branched, often anastomosing, (1.2-)1.5-3.5(-4) μm wide at base, the apical cells (2.5-)3.5-7.5(-8) μm wide. Asci 8-spored, clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, narrowly ellipsoid, (7.5-)9.5-13(-15) x (3.5-)4.5-5.5(-6.5) μm, the equatorial thickening (“septum”) (2-)3-4.5(-5) μm, > 1/3 of spore length. Photobiont chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-. Chemistry: thallus and apothecia with parietin (major), fallacinal, emodin, teloschistin and parietinic acid (minor), corresponding with chemosyndrome A of Søchting (1997).
Note: a well-distinct taxon of the extremely critical C. saxicola complex, found on steeply inclined surfaces of calciferous rocks (limestone, dolomite, calcareous schists) in open habitats; certainly more widespread in Italy. For further details see Gaya & al. (2001).