Caloplaca crenularia

A species of well-lit siliceous or weakly alkaline rocks and old walls, the shiny margins of the apothecia and the persistently terracota discs helping to distinguish it from the closely related C. ceracea. Recently recorded on quartz conglomerate boulders on Cefn Bryn.

Listed by Alan Orange in Flora of Glamorgan (Wade et al, 1994).