Description: Thallus crustose, usually well-developed and thinly episubstratic areolate, greyish white, sometimes poorly evident. Apothecia biatorine, sessile, clustered, angular, 0.5-1 mm across, with a brownish red, flat to slightly convex disc, and a thin, black, persistent, slightly flexuose proper margin. Proper exciple without algae, blackish green in outer part, K-, N+ purple-red, colourless within; epithecium orange-brown, K+ violet-red; hymenium colourless, 60-85 μm high; paraphyses simple or sparingly branched in upper part, with slightly swollen apical cells; hypothecium colourless, inspersed with oil droplets, c. 80 μm high. 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, ellipsoid, 10-14 x 5-7 μm, the equatorial thickening (“septum”) 3-4(-5) μm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, N+ faintly violet. Chemistry: cinereorufa-green pigment in thallus and apothecial margin; epithecium with non-chlorinated anthraquinones.
Note: related to C. exsecuta, known from the locus classicus in Tyrol, Poland, a single locality in the French Maritime Alps (Roux & coll. 2014), and from dry-warm sites in central Sardegna and in Piemonte. The identification of the Sardinian collection is not completely certain (Nimis & Poelt 1987: 60). A detailed discussion of this species was provided by Wilk & Flakus (2006).