Description: This small species occurs mostly on twigs of basic trees and shrubs. It is extremely common on ash, where it occurs with Lecania cyrtella and L. naegelii. Twigs should be inspected along their final 30cm. Sometimes the small, orange, crowded discs are restricted to just one or two individuals; which are less easy to spot. It is also frequent on elder. Generally, the species is widespread throughout Ireland.

Key Identification Features:

• The twig habitat, clustering small orange fruits and K + crimson reaction should distinguish it
• The very small fruits and indistinct thallus separate it from Caloplaca cerina, which occurs in similar habitats. This latter species has a more obvious grey to greenish-grey thallus and a thick thalline margin
• Caloplaca cerinelloides is very similar, but is strongly attracted to lime dust sources. It has eight spores/ascus, whereas C. cerinella has considerably more. It has yet to be recorded in Ireland, but should be searched for in suitable habitats.

Original text submitted by Simon Davey

Distribution Map from NBN: Athallia cerinella at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Athallia cerinella at iNaturalist World Species Observations database.