A crustose species with a white to pale grey thallus that is smooth, cracked or granular. The apothecia are black, but very white-grey pruinose which makes the discs look pale.
Thallus: C-, K-, UV-
In Scotland, Diplotomma alboatrum is found on calcareous rock and mortar in lowland and coastal regions. BLS distribution map
scottishlichens.co.uk 