An eye-catching, crustose species with a light to medium grey, thick thallus that can be smooth or warted, and it often has a thin, dark prothallus. It usually is fertile with the apothecia gathering in the central part of the thallus. These apothecia are large with a black and thick, grey, contorted or crenulate margin.
Cortex: C-, K+ yellow, UV+ ice-blue
In Scotland, Tephromela atra is widespread except from parts of the Highlands and south of the Central Belt. It grows on well-lit siliceous or slightly calcareous rocks and walls, and is very common on both coastal rocks and gravestones. BLS distribution map
Tephromela atra may be parasitised by Lecanora sulphurea.
Tephromela atra can be distinguished from Lecanora gangaleoides on basis of its cortorted apothecia with sometimes crenulate margins.
scottishlichens.co.uk 