Lecanora campestris (Schaer.) Hue subsp. campestris s.l.
Thallus crustose, generally circular, up to 10 cm in diameter, more or less strongly warty or strongly granular, areolate, sometimes not very thick and poorly developed (the apothecia then appear isolated or in small groups on the substrate), dirty whitish, pale grayish, pale greenish-gray, grayish, pale bluish-gray, bordered by a whitish fimbriated hypothallus that is sometimes barely visible (N.B. On horizontal surfaces the thallus is often invaded by algae and it can become olive-colored or greenish-brown). Apothecia numerous, most often grouped towards the center, sessile, 0.5-1.5 mm in diameter, flat to slightly convex disc, smooth, red-brown, dark red-brown, orange-brown sometimes tinged green, often blackish at the end, margin clear, whitish, smooth and more or less convoluted. Asci of 45-65 x 14-20 µm according to our measurements, with 8 spores. Spores simple, broadly elliptical, 10-15 x 6-9 µm according to the literature, 11-15 x 6-9 according to our measurements. Photobiont: Trebouxia. C-, K+ yellow, KC+ yellow, P+ very pale yellow and often barely visible. Nitrophilous species not particularly maritime but common on weakly acidic rocks or on old walls along the sea, sometimes cement, concrete, asphalt, PVC furniture, etc.