Distribution: N - Frl (Baruffo & al. 2006), TAA (Caniglia & al. 2002, Nascimbene 2005b, 2006c, 2007b), Lomb (Nascimbene 2006, Abramini & al. 2008), Piem (Baruffo & al. 2006), VA (Piervittori & Isocrono 1999, Baruffo & al. 2006), Emil (Fariselli & al. 2020), Lig (S- L43503). C - Tosc (Baruffo & al. 2006), Umb (Panfili 2000, Ravera & al. 2006), Laz, Sar (Nöske 2000, Zedda 2000a, 2002, Zedda & al. 2001, Baruffo & al. 2006). S - Cal (Puntillo 1996).
Description: Thallus leprose, pale yellowish (at least in marginal parts) to cream-coloured, forming a very well-delimited, lobed, membrane-like rosette, the lobes to 3.5 mm wide, with raised, often wavy margins, and a brownish hypothallus. Surface covered in a soft mass of soredia-like, 40-120 μm wide granules, sometimes gathered into up to 300 μm wide aggregates, especially in the central parts of thallus, often with short projecting hyphae. Medulla distinct, white in upper part, brownish in lower part, forming a grey to brown hypothallus-like layer. Photobiont chlorococcoid. Spot tests: K+ yellow to orange (rarely K-), C- or C+ yellow, P+ orange-red, UV-. Chemistry: pannaric acid (major) with satellite dibenzofurans (minor to traces), roccellic/angardianic acid (rarely absent), atranorin (major to trace).
Note: on steeply inclined to weakly underhanging surfaces of siliceous rocks, sometimes on epilithic bryophytes, much more rarely on bark, often forming monospecific stands; certainly much more widespread in Italy.
Growth form: Leprose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)