Description: Thallus crustose, episubstratic, rimose-areolate to areolate, up to 1.2 mm thick, white to pale yellowish grey, forming up to 5 cm wide patches, sometimes delimited by a black prothallus. Medulla white, I-. Apothecia: black, lecideine, subimmersed to sessile and more or less constricted at base, round to irregular in outline, 0.5-1(-1.6) mm across, with a flat to finally slightly convex, epruinose disc, and a slightly glossy, finally sometimes excluded proper margin. Proper exciple 35-70(-90) μm thick laterally, widely extending below the hypohecium in older apothecia, dark throughout (greenish to blackish brown in outer part, brown in inner part); epithecium bluish or blackish green, c. 10 μm thick; hymenium colourless, 55-80 μm high, sometimes with crystals in lower part, I+ blue; paraphyses easily made free in K, mostly simple, rarely sparingly branched in upper part, c. 2.5 μm thick at mid-level, the apical cells up to 5 μm wide; hypothecium colourless in upper part, yellowish brown in lower part, up to 250(-320) μm high. Asci 8-spored, clavate, with an intensely I+ blue tholus penetrated by a weakly amyloid, broadly cylindrical axial mass, and a poorly developed ocular chamber, Lecidella-type. Ascospores 1-celled, hyaline, thick-walled, ellipsoid, 12-15 x 5.5-8 μm. Pycnidia black, immersed. Conidia thread-like, curved, 12-32 x c. 1 μm. Photobiont chlorococcoid. Spot tests: thallus K-, C+ and KC+ fleeting red turning orange, P-. Chemistry: aotearone, 2,5,7-trichloro-3-O-methylchloronorlichenxanthone (major), 3-O-methylasemone, isoarthothelin and thiophanic acid (traces).
Note: a silicicolous, mainly coastal species described from Greece; to be looked for in Mediterranean Italy.