Description: Thallus crustose, episubstratic, areolate, grey to greyish brown, developing on the thalli of Dimelaena oreina. Epinecral layer 15-30 μm thick; cortex paraplectenchymatous, 30-60 μm thick, with abundant small crystals dissolving in K (yellow solution: atranorin); medulla white, I-. Apothecia lecideine, black, 0.2-0.7(-0.8) mm acrosss, adnate to sessile and constricted at base, with a flat to convex disc and a prominent, finally excluded proper margin. Proper exciple dark brown, N-, with crystals reacting P+ orange, dispersa-type, of radially arranged hyphae, the inner part of long-celled, parallel, strongly agglutinated and thick-walled hyphae, the outer part of short-celled, isodiametric hyphae without intercellular spaces; epithecium dark brown, N-; hymenium colourless, without oil droplets, 80-100(-150) μm high; hypothecium dark brown, up to 150 μm high. Asci (6-)8-spored, clavate, Bacidia-type. Ascospores 1-septate, brown, ellipsoid, 12-16 x 6.5-7.5 μm, Physconia-type when young, Buellia-type when mature, the wall microrugulate. Pycnidia black, semi-immersed in the thallus. Conidia bacilliform, 5-7 x c. 1 μm. Photobiont chlorococcoid. Spot tests: cortex K+ yellow; medulla C-, KC-, P+ orange. Chemistry: atranorin (major) medulla with pannarin.
Note: a xeric subtropical lichen of hard siliceous rocks, starting the life-cycle on Dimelaena oreina; described from North America, but also found in the Mediterranean Region.
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)