Synonyms: Dirina repanda f. isidiosa Werner; Dirina repanda f. lecideina H. Olivier; Dirina repanda f. sorediata Werner; Dirina repanda var. crassa Maheu & A. Gillet; Dirina repanda var. schistosa Bagl.; Dirina repanda var. stipitata Nyl.; Dirina schistosa (Bagl.) Nyl.; Lecidea praerimata Nyl.
Distribution: N - Lig. C - Tosc, Sar (Tehler & al. 2013). S - Si (Tehler & al. 2013)
Description: Thallus crustose, episubstratic, smooth to slightly rugose-verruculose, epruinose, grey-brown to cream-coloured, 0.1-1.5 mm thick, sometimes sorediate. Cortex 30-60 µm thick; medulla chalky white, with loose hyphae near the substratum. Soralia present in sterile specimens, punctiform to maculiform. Apothecia lecanorine, sessile, constricted at base, round to angular in outline, up to 2 mm across, with a dark-grey to grey-black, but ususally densely white-pruinose disc, and a thick, often wavy proper margin. Proper exciple inconspicuous; epithecium brownish, with crystals visible under polarized light; hymenium colourless; paraphysoids unbranched or sparsely branched, 1-2 µm thick, the apical cells 2-3 µm wide; hypothecium thick, black. Asci 8-spored, clavate, bitunicate, the apex thickened with a small internal K/I+ blue ring. Ascospores 3-septate, hyaline, fusiform, straight or slightly curved, 18–24 x 5-6 µm. Pycnidia black, immersed or slightly protruding. Conidia thread-like, sickle-shaped. Photobiont trentepohlioid. Spot tests: thallus K-, C+ faintly red, KC+ red, P-; medulla and soralia C-; apothecial disc C+ red. Chemistry: erythrin, lecanoric acid, plus unidentified substances.
Note: a mainly western, Mediterranean-Atlantic species of siliceous rocks which occurs also in central Europe, along the Atlantic coast and in the British Isles, with both fertile or pycnidiate and sorediate specimens.