Description: Thallus crustose, episubstratic, deep yellow-orange, thin, continuous to minutely rimose-areolate, more rarely poorly developed and film-like, sometimes delimited by a pale yellow prothallus, rarely indistinctly lobed at margins. Isidia usually very numerous, small, crowded, granular, finger-like to branched-coralloid, often forming a thin to thick, coarsely areolate crust. Apothecia rare, 0.4-0.8 mm across, rounded, with an orange to deep orange, mostly flat disc, and a somewhat paler, thin, finally often excluded proper margin. Epithecium orange, K+ red; hymenium colourless; paraphyses lax, branched, the apical cells up to c. 4 μm wide; hypothecium colourless. Asci 8-spored, clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, 11-15 x 5-8 μm, the equatorial thickening (“septum”) 1-4 μm (up to c. 1/4 of spore length). Photobiont chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-. Chemistry: different anthraquinones.
Note: a mainly Atlantic species confined to relatively dry, sheltered recesses in the xeric-supralittoral zone on siliceous rocks, known from a single, very peculiar station in Sardegna (Punta Falcone), hosting several other "Atlantic" lichens. According to Vondrák (in litt.) this species is a member of Haloplaca.
Growth form: Crustose placodiomorph
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by isidia, or isidia-like structures (e.g. schizidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)