Distribution: N - VG, Frl (TSB 17372), TAA (Schultz 2000), Piem (Clerc & al. 1999), Lig (TSB 34678). C - Abr (Nimis & Tretiach 1999, Caporale & al. 2016), Mol (Caporale & al. 2008), Sar (TSB 6221). S - Camp (Nimis & Tretiach 2004), Pugl (Nimis & Tretiach 1999), Cal.
Description: Thallus small-foliose to squamulose-umbilicate, polyphyllous, gelatinous when wet, black, dull to glossy, very rarely with patches of grey pruina, forming regular to irregular up to 3 cm wide cushions, soon covered in minute, globose 0.1-0.3 µm wide isidia, densely lobulate, the lobules at first adpressed, but soon ascending to erect in central parts of thallus, 1-2 mm wide at base and 3-4 mm wide at tips, broadly rounded at first but soon divided, with ascending, thicker margins; lower surface attached by a central holdfast. Thallus 0.2-0.4 µm thick, the outer part 50-70 µm thick, formed by short-celled, mainly anticlinally oriented hyphae enclosing the photobiont cells, the medullary part of loosely to densely arranged (forming a 50-100 µm thick compact strand), 1-2 µm thick hyphae with cylindrical cells, lacking photobionts. Apothecia thallinocarps, rare, marginal to apical, 0.3-0.6 mm wide, sunk in thallus and difficult to recognize unless when wet, with a rough disc and a up to 50 µm wide, indistinct thalline margin. Proper exciple absent; hymenium 110-150 µm high, separated into partial hymenia by intrusions of wedge-shaped, sterile thalline tissue, covered by a continuous layer of sterile tissue separated by the pore-like discs of the partial hymenia, I+ blue turning wine-red; subhymenium hyaline, continuous, 50(-100) µm thick, I+ blue. Asci 16-24-spored, with a thin, one-layered, non-amyloid wall, an amyloid external apical cap, and passive spore discharge via apical rupturing. Ascospores 1-celled, hyaline, broadly ellipsoid, 6-8 x 3-4 µm. Pycnidia rare, globose, immersed. Conidia ellipsoid, 4-5 x 1.5 µm. Photobiont cyanobacterial, chroococcoid, with a few cells measuring 6-12 x 6-10 µm, penetrated by haustoria and surrounded by a brownish gelatinous sheath. Spot test: all negative. Chemistry: without lichen substances.
Note: on steeply inclined surfaces of calcareous or base-rich siliceous rocks with water seepage after rain; certainly more widespread in the Alps and in the Apennines. See note on L. iodopulchra.