Arthonia varians is a parasitic lichen of Glaucomaria (=Lecanora) rupicola, taking over and blackening the apothecia of that species and retarding their development. 

Where its host Glaucomaria rupicola is present.

All year round.

Widespread and evidently common where the host occurs, but evidently under-recorded.

Status in Leicestershire and Rutland not known.