Distribution: C - Sar (Crespo & al. 2004). S - Si (Nimis & al. 1994, Ottonello & Salone 1994, Crespo & al. 2004).
Description: Thallus crustose-placodioid, bluish white-pruinose, sorediate, forming orbicular, often confluent rosettes up to 3(-5) cm in diam., often covering large surfaces. Central parts areolate, marginal lobes contiguous, 1-5 mm long, 0.3-1 mm wide. Soralia small (c. 0.2 mm across) circular, well-delimited by a thin margin, often raised, with granulose soredia more or less concolourous with thallus. Apothecia unknown. Pycnidia dark, immersed, globose, with pleurogenous conidogenous cells. Conidia cylindrical, 3.8-5 x c. 1.3 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mainly western, Mediterranean-Atlantic species growing on soft calcareous rocks wetted by rain and exposed to humid maritime winds, mostly on horizontal surfaces, often forming large monospecific stands. It is locally abundant along the western coasts of Sicilia and Sardegna.
Growth form: Crustose placodiomorph
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)