Teloschistaceae Athallia holocarpa sens str. (Caloplaca holocarpa sens str.) Growth type crustose Chemical results: K+ crimson Widespread on dusty siliceous rocks, mortar and concrete. Also found on dusty tree trunks and worked timber. Thallus yellowish-grey, thin, cracked and areolate or sometimes only visible round the (usually numerous) apothecia. Discs yellow-orange to bright orange, the margins becoming scarcely visible. Asci 8-spored, spores 10-13 x 5.5-7.5 µm, septum 3.6-5.4 µm wide. Micrograph below.

Micrograph

Caloplaca holocarpa sens str
Pamphill Green, Dorset. January 2016