Description: Thallus crustose, endosubstratic to episubstratic, continuous to finely rimose, cream-coloured, brownish or grey, without a distinct prothallus. Apothecia immersed in the thallus and often surrounded by a circular crack, 0.2-0.7 mm across, rounded or irregular in outline, with an initially concave, then flat, pink, yellow-pink or pale brown disc, and a rather evident, whitish proper margin. Proper exciple colourless; epithecium colourless or pale yellowish brown, K-, N-; hymenium colourless, 100-120 µm high; paraphyses simple or sparingly branched, submoniliform in upper part, the apical cells not swollen; hypothecium colourless. Asci 8-spored, cylindrical-clavate, the outer coat I+ blue, but the inner walls and apical dome K/I-. Ascospores 1-celled, hyaline, ellipsoid, 10-24(-26) x 7-17(-19) µm. Pycnidia immersed, pale-walled. Conidia bacilliform. Photobiont chlorococcoid (Asterochloris), the cells <15 µm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on hard calcareous rocks, especially compact limestone, most frequent in the Alps, but also present in the Mediterranean mountains, probably occurring throughout the country. According to Lutzoni & Brodo (1995) and Roux & coll. (2014), this is just a phycotype of H. epulotica with trebuxioid algae.