A crustose species with a grey or green-grey, smooth or warted thallus and a white prothallus. The apothecia have a black disc and a wide thalline margin. The discs are persistently convex and the margins do not usually become contorted. Where the thallus is damaged or picked away, the orange lower medulla is often visible.
Thallus: C-, K+ yellow, UV- or pale orange
In Scotland, Lecanora gangaleoides is widespread in coastal and lowland regions where it is found on hard siliceous rocks in both exposed and shaded sites. BLS distribution map
Lecanora gangaleoides can be distinguished from Tephromela atra on basis of the darker green-grey and often more warted thallus and the apothecia that are persistently convex and that have margins that do not usually become contorted.
scottishlichens.co.uk 