Distribution: N - VG, Frl (Breuss 2008), Ven (Lazzarin 2000b, Nascimbene & Marini 2007), TAA (Nascimbene & al. 2007b, Spitale & Nascimbene 2012), Lomb (De Vita & Valcuvia 2004), Piem (Isocrono & al. 2004), Emil, Lig (Giordani & al. 2016). C - Tosc, Laz (Nimis & Tretiach 2004), Abr (Nimis & Tretiach 1999). S - Camp (Nimis & Tretiach 2004), Pugl (Nimis & Tretiach 1999), Si (Grillo 1998, Grillo & al. 2001, 2009, Grillo & Caniglia 2004, Caniglia & Grillo 2005, 2006).
Description: Thallus crustose, endolithic, whitish to brownish grey, smooth, delimited from conspecific thalli by a crack, a whitish line, or a row of brown pycnidia. Upper cortex a pseudocortex, formed by a thin prosoplectenchyma intermingled with microcrystals, sometimes with one layer of slightly pigmented cortical cells at top; medulla prosoplectenchymatous, white, K/I+ violet, without macrospheroids. Perithecia black, 0.28-0.5 mm across, not covered by thallus, the apex flat or usually concave, the base leaving shallow pits in rock. Involucrellum well-developed, thick, flanking the upper half of exciple, the pigment dark reddish brown, K+ dark brown; exciple brown in upper part, pale below. hamathecium of periphyses and periphysoids, interascal filaments absent; hymenial gel hemiamyloid, I+ red (I+ blue at very low concentrations of I), K/I+ blue. Asci 8-spored, clavate, I-, fissitunicate, the wall thickened above, with an ocular chamber, dehiscent by extrusion of an endotunica to form a delicate rostrum. Ascospores 1-celled, hyaline, oblong to ellipsoid, 15.5-20(-23.5) x 6.5-9 μm, often with a to 1.5 μm thick perispore. Pycnidia frequent, 0.06-0.1 mm wide, often numerous, appearing as black to brown dots, scattered or often arranged in lines at the thallus edge. Conidia rod-shaped, 3.3-4.5 x 0.8-1.2 μm. Photobiont chlorococcoid. Spot tests: all negative. Chemistry: no lichen substances.
Note: on steeply inclined surfaces of hard calcareous rocks, mainly limestone, in rather shaded situations, with a wide altitudinal range, reaching the eu-Mediterranean belt in particularly humid and shaded stands.