Caloplaca ruderum (Malbr.) J. R. Laundon

    Thallus crustose, thick, margin not lobate, made of granules assembled in large bumpy patches of swollen or markedly convex areoles, white-pruinose especially at the begginning, pale yellow-ochre, yellowish il in the sun, yellow-greenish, greenish-gray (never bright orange). Apothecia more or less numerous, 0,5-1,5 mm  diam., at first urceolate or crater-shaped giving rise to disc, pale orange-salmon, margin thick, thallus concolourous. Ascospores ellipsoid, polarilocular,  septum 3-5 µm wide, between 1/5-1/3 of length of the ascospore, 10-15 x 6-8 µm. Photobiont : trebouxioide. All parts K+ purple. In our prospection area, tends to be coastal, on calcareous rocks  and also on old walls with lime/mortar, supports polluted environments. N.B. Do not confuse with some flourishing forms of Caloplaca maritima et de Caloplaca marina.