Description: Thallus crustose, episubstratic, areolate, of two colour forms, yellow and orange, often occurring together. Areoles (70-)80-155(-210) μm thick, (0.24.)0.3-0.9(-1.2) mm wide, entirely covered in blastidia/soredia of limonia-type (laminal blastidia, and true soralia produced from cracked blastidia or after the blastidia have eroded); blastidia/soredia (23-)30-50(-61) μm in diam. Cortex indistinct, of 1-2 layers of cells. Apothecia frequent, zeorine, yellow or orange, 0.4-0.65 mm across, with a slightly concave to slightly convex disc, and an often sorediate/blastidiate thalline margin. Proper exciple (50-)60-100(-110) μm thick; epithecium brownish yellow, K+ red, hymenium colourless, 70-80 μm high; paraphyses simple or sparingly branched, the apical cells up to 5(-6) μm thick; hypothecium colourless. Asci 8-spored, narrowly clavate, Teloschistes-type. Ascospores 1-septate, polarilocular, hyaline, ellipsoid, thick-walled, 11-16 x 6-9 μm, the septum 3.5-4.5 μm thick (c. 1/3 of ascospore length). Pycnidia yellow-orange. Conidia (1.5–)2-3 x c. 1 μm. Photobiont chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-. Chemistry: thallus and apothecia with parietin (major), fallacinal, emodin, teloschistin and parietinic acid (minor), corresponding with chemosyndrome A of Søchting (1997).
Note: on limestone or more rarely on similar anthropogenic substrates; widespread in the Alps and elsewhere in Europe, but distribution still insufficiently documented; to be looked for in Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)