Caloplaca scotoplaca (Nyl.) H. Magn. Cf.

    Tallus crustose, thin, blurry, cracked-areolate, margin not lobate, dark grey-brown, dark brown. Apothecia usually numerous, irregular, 0.2-0.4 mm diam., disc plane later subconvex, dark red, concolourous persistent margin. Ascospores polarilocular, septum 2-5 µm, to 1/4-1/3 of ascospore length, 10-13 x 3-8 µm. Photobiont : trebouxioide. Apothecia : K+ purple. Species displaying Atlantic trends on nutrient-rich rocks and stones of walls. Considered here according to French authors, easily confused with Caloplaca crenularia which apothecia are bigger aand darker-(red),  margin excluded at late, and ascospores bigger; and with Caloplaca arenaria which thallus is evanescent, pale grey and blurry, has bright red apothecia and narrower ascospores.*