Description: Thallus crustose, thinly episubstratic, continuous to partially areolate, white to grey-white. Apothecia lecanorine, up to 0.5 mm across, with a pale brown to black, soon convex disc, and a thin, usually persistent, white-grey to pale brown thalline margin. Thalline exciple well-developed, rich in algae; epithecium brown to red-brown; hymenium colourless or brownish in upper part, 50-60 µm high; paraphyses coherent, simple, 1.5-2 µm thick at base, the apical cells pale to dark brown, 2-3(-4) µm wide; hypothecium colourless. Asci 8-spored, clavate, with a K/I+ blue apical dome penetrated by a narrow, K/I- apical cushion surrounded by a narrow, deeply K/I+ blue zone, the wall K/I- but surrounded by an I+ red-brown, K/I+ blue outer layer, the ocular chamber relatively small, Biatora-type. Ascospores 1-septate, hyaline, distinctly curved and kidney-shaped, 12-17 x 4-6 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a species recalling L. cyrtella, but with strongly curved ascospores; mostly on bark of broad-leaved trees; widespread in Europe but altogether rare; from the Alps there are some scattered records, mostly in the montane belt; to be looked for in Italy.