Caloplaca arcis. This is a photograph of a lichen taken in Soest Churchyard in the Netherlands, and was named by Dutch lichenologists as Caloplaca britannica, which in  the UK we believe it isn't. The Lichen Flora states tha the entity growing in churchyards which has been confused with C. britannica is C. arcis. This is a split from  Caloplaca citrina, of which more later. A single, marginal lobe can be seen fairly clearly towards tyhe top right, which is a feature of C. arcis which has smaller lobes in the thallus than is typical for C. britannica. It seems thast C. arcis is most frequently seen in churchyards and on articial habitats.