A placodioid species that usually forms neat, closely adpressed, bright orange rosettes. The lobes are long, convex, but may be slightly flattened near the tips. Apothecia gather in the centre of the thallus, and are orange with paler margins which often become excluded.
Thallus and apothecia: K+ purple
Caloplaca thallincola can be found along most of the Scottish coastline where it grows on hard, siliceous rocks in the mesic-supralittoral zone. BLS distribution map
Caloplaca thallincola is often found overgrowing Hydropunctaria maura, alongside Lecanora helicopis, and more rarely with Caloplaca marina.
Caloplaca thallincola is distinguished from Caloplaca flavescens on basis of its brighter, cleaner colour, and the extension of the lobes further towards the centre of the thallus.
scottishlichens.co.uk 