Thallus very variable; rather smooth, even and continuous or granular-verrucose, almost white or yellow-grey to yellow-green in sunny, exposed sites, becoming grey-green in shade, rarely almost absent, at times forming mosaics. Prothallus black or blue-black, sometimes very prominent. Soralia and isidia not present. Anamorph: conidiomata rarely seen, pycnidia, immersed in the thallus with the black ostiolar region slightly protruding. Conidiophores not clearly developed, the conidiogenous cells developing in a palisade from the inner surface of the conidioma wall; rather irregular in shape, broadly cylindrical, tapering or doliiform, probably proliferating percurrently but with collarette absent and periclinal thickening not obvious. Conidia 12-15 x ca 1 µm, filiform, strongly curved, aseptate, hyaline, thin-walled, smooth. Teleomorph: ascomata apothecia, to ca 1 mm diam., closely appressed, rounded to irregular, at first plane, later convex; occasionally in clusters on a common melanized base. Disc black in exposed, well-lit situations, sometimes pale blue-black, brown-red, cream-yellow or ± piebald with a darker true exciple (the variation possibly associated with shade). True exciple persistent, flexuose, finally excluded, concolorous with the disc. Epithecium and edge of true exciple blue-green to dull grey-blue [visible in sections], with crystals that dissolve in K. Hymenium 40-70 μm tall, sometimes with crystalline inclusions in the lower part and in the hypothecium. Hypothecium brown-orange, rarely colourless, intensifying to bright red-brown in K. Interascal tissue of rather broad and thick-walled unbranched non-capitate paraphyses. Asci cylindric-clavate, thick-walled, short-stalked, with a very large apical cushion staining dark blue in Lugol's iodine, with an inner non-staining column that does not reach the apex, similar to that seen in Bacidia species; 8-spored. Ascospores arranged biseriately, 10-17 × 6-9 μm, ellipsoidal to ovoid-ellipsoidal, fairly thick-walled, hyaline, without a gelatinous sheath or epispore. Chemistry: thallus C+ orange, K+ yellow, KC+ yellow, Pd– (reactions often faint, arthothelin, granulosin, ± 4,5 dichlorolichexanthone).