Description: Thallus crustose, episubstratic, rather thick, areolate to verrucose-areolate, whitish to rarely pale brown, sometimes delimited by a dark prothalline line. Medulla white, not amyloid, I-. Apothecia black, lecideine, epruinose or slightly pruinose, 0.3-1(-1.5) mm across, initially immersed, then slightly prominent, with a black, flat to convex disc, a thick proper margin, and a pseudothalline margin particularly evident in young apothecia. Proper exciple brown in outer part, colourless to pale brown in inner part, of radiating hyphae; epithecium brown; hymenium colourless, K/I+ blue; paraphyses simple, c. 2 μm wide at base, slightly capitate and to 3 μm thick at apex; hypothecium brown. Asci 8-spored, clavate, with a thick apex, amyloid, with a distinct axial mass, Bacidia-type. Ascospores 3-septate, sometimes with a single longitudinal septum, brown, ellipsoid, 14-25 x 8-11 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C- KC-, P-. Chemistry: without lichen substances.
Note: mostly on the smooth bark of deciduous trees, much more rarely on lignum, at relatively low elevations. According to Roux & coll. (2014) this is a good species, differing from D. alboatrum in the larger apothecia with a thick margin. The Italian sample, identified by H. Sipman, was collected by V.J. Grummann near the Beach of Savio, on Platanus.