Caloplaca aurantia (Pers.) J. Steiner
Thallus placodioid, rosette shaped, 5-10 cm diam., composed of long, flat lobes, closely appressed, partially or entirely rounded (margins seem to have been ironed), 1-3 mm wide, ; lobe-ends rounded and flat, sligthly furrowed, bright yellow, yellow,-orange, cocklade-like with an outer pale cream ring and a central darker area cracked-areolate, in part brown-orange due to the presence of apothecia. Apothecia, confined to the central area, usually abundant and crowded, to 1-1.5 mm diam., discs flat to slightly convex, brown-orange, with a distinct thin orange-yellow thalline margin. Ascospores polarilocular, typically lemon-shaped, 10-13 x 8-10 µm. Photobiont : trebouxioide. Thallus and apothecia K + purple. On well-lit limestone or calcareous stone walls. See Caloplaca flavescens much more frequent on nutrient-rich habitats and notably on mortar of walls, thallus with tight, convex lobes without furrows. See also taxa of Caloplaca saxicola complex with different spores.