Caloplaca dalmatica. This is a common species most often met with on the south, limestone walls of churches. It is close to Caloplaca ruderum, buit the habitats differ, and dalmatica usually has a denser placoid thallus made up of yellower areolae.
Species category:
Photo:
![](https://psl.brc.ac.uk/sites/default/files/upload/Caloplaca%20dalmatica%202.jpg)