Denkschr. math.-naturw. Cl. K. Akad. Wiss. Wien, 71: 95, 1902.
Distribution: C - Sar. S - Si.
Description: Thallus crustose, episubstratic, sulphur yellow, sometimes finely white-pruinose, areolate. Areoles flat, 0.4-1.5 x 0.2-0.5 mm, scattered to usually contiguous, mostly angular. Upper cortex 30-50 µm thick; algal layer uneven, interrupted by hyphal bundles; medulla white. Apothecia aspicilioid or lecanorine, immersed in the thallus, mostly round, 0.3-0.6(-0.8) mm across, with a dark brown disc and a more or less evident thalline margin. Epithecium brownish; hymenium colourless, up to 120 μm high, I+ blue turning reddish; paraphyses conglutinated, hardly swollen at apex; hypothecium colourless. Asci 100-200-spored, clavate, the apical dome K/I-. Ascospores 1-celled, hyaline, broadly ellipsoid to subglobose, 3.5-4.5 x 2-3.5 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, UV+ orange. Chemistry: rhizocarpic acid.
Note: a xeric subtropical species of igneous rocks in dry-warm areas, ranging from Macaronesia through southern Europe to Arabia. The species could be confused with forms of A. heufleriana which are poor in norstictic acid, previously treated as A. heufleriana var. massiliensis (Roux in litt.).
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)