Description: This large, spreading, crustose species of nutrient-rich rocks and walls occurs widely throughout Ireland: near the sea, alongside lough margins and more especially, on river boulders. The grey thallus with a roughened, warted surface looks rather like a scruffy or crumpled version of A. calcarea (described elsewhere) which is much smoother and of an ‘ironed’ appearance and never breaks up into island pieces (areoles) of thallus.

Key Identification Features:

• The darker, more congested, cracked thallus with black discs having an irregular margin helps suggest this species
• Unlike Aspicilia cinerea which is Pd+ orange and K+ red, it is both K- and Pd-.

Original text submitted by Simon Davey

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

iNaturalist: Circinaria caesiocinerea at iNaturalist World Species Observations database.