Yellow lichen on limestone

Yellow lichen on limestone

Observation - Yellow lichen on limestone. Description: Yellow, placodioid lichen with some pruina on lobes growing on oolitic limestone church window sill. Darker areolate thallus in middle. For colour comparison, picture (ii) shows the lichen on left next to (what I think are) Caloplaca flavescens lichens

Yellow, placodioid lichen with some pruina on lobes growing on oolitic limestone church window sill. Darker areolate thallus in middle. For colour comparison, picture (ii) shows the lichen on left next to (what I think are) Caloplaca flavescens lichens on right. Possibly Candelariella medians