Distribution: C - Tosc (TSB 35238), Sar. S - Camp (Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl (Nimis & Tretiach 1999, Durini & Medagli 2004), Bas (Bartoli & Puntillo 1996, 1998), Cal (Puntillo 1996), Si (Nimis & al. 1994).
Description: Thallus crustose, partly endosubstratic, partly thinly episubstratic, continuous, smooth to minutely rugose, white or pale grey with a pinkish hue (which disappears in herbarium specimens), without a clear prothallus. Apothecia totally to 3/4 immersed in the thallus, 0.2-0.5 mm across, at first perithecioid, finally with a slightly expanded, concave to flat, beige-pink to pale brown disc surrounded by a thick, whitish, radially fissured proper margin. Proper exciple thin, more or less colourless; hymenium colourless, 130-150 µm high, I-, K/I+ blue; paraphyses simple, 2-3 µm thick at mid-level, the apical cells not or only slightly widened; hypothecium colourless. Asci 8-spored, clavate, thin-walled, K/I+ blue. Ascospores 3-5- transversally septate, sometimes finally with 1(-2) additional longitudinal septa, hyaline, ellipsoid, 18-31 x 7-18 µm, surrounded by a gelatinous perispore (best visible in K, or adding Indian ink to the preparation). Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on sheltered, often north-facing surfaces of calcareous cliffs, usually near the sea. The genus Neopetractis differs from Petractis in having a different phylogenetic position and a different photobiont (Ertz & al. 2021).