Synonyms: Lecanora agardhanioides A. Massal.; Lecanora agardhanioides var. cilophthalma A. Massal.; Lecanora agardhanioides var. dealbata A. Massal.; Lecanora agardhanioides var. melanophthalma A. Massal.; Lecanora agardhanioides var. microstigma A. Massal.; Lecanora agardhanioides var. pacnodes A. Massal.; Lecanora agardhiana Ach. subsp. agardhiana; Myriolecis agardhiana (Ach.) Sliwa, Zhao Xin & Lumbsch subsp. agardhiana
Description: Thallus crustose, endosubstratic or very thinly episubstratic and poorly evident. Apothecia lecanorine, immersed in pits in the rock at least when young, 0.2-0.6 mm across, with a flat, dark brown to black, often pruinose disc and a thin, smooth, entire, sometimes finally excluded thalline margin. Thalline exciple corticate, the cortex usually more or less obscured by crystals insoluble in K, but soluble in N, the medullary part with a few algae only; epithecium brownish or olive, not granular, K-, N+ pink or purple; hymenium colourless, 60-70 μm high; paraphyses slender, simple, free in K; hypothecium colourless, without granules. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, (7-)9-12 x (4-)5-6(-7.5) μm. Photobiont chlorococcoid. Spot tests: thallus (apothecial margin) K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a widespread holarctic lichen found on horizontal to weakly inclined surfaces of hard limestone and dolomite, with a wide altitudinal range; the distinction from other related species still needs further study.