Caloplaca from Brecon Beacons 25th March

Found on 25th March 2016 on a gate post this Caloplaca was not found to be identifiable with my level of expertise currently. A shortlist was drawn up using apothecia size (1mm) and habitat giving Caloplaca citrina as the best guess. Both the thallus and apothecia are K+ purple eliminating C. virescens and C.cerina. Apothecia colour elimnated herbidella. There were few polaricula spores the largest measured 15x4.5µm. Some of the paraphyses had swollen tips measuring 3.75µm