Description: Thallus squamulose, the squamules densely imbricate, small and thin, 1-3 mm wide and 0.1-0.2 mm thick, flat to undulate, incised-lobulate; upper surface greenish grey to medium brown, somewhat pruinose; lower surface at first whitish, then often blackening, attached by colourless to pale brown 3-5 µm thick rhizohyphae, usually concentrated in central parts. Upper cortex 20-45 µm thick, with roundish-angular cells; epinecral layer very thin or lacking; medulla with many globular cells; lower cortex not clearly delimited from medulla. Perithecia subglobose, up to 0.5 mm across, immersed in the squamules, without involucrellum. Exciple pale to brown, darkened towards the ostiole. Asci 8-spored, clavate, I-, fissitunicate, the wall thickened above, Verrucaria-type. Ascospores 1-celled, hyaline, ellipsoid, 11-14 x 6-7 µm, biseriately arranged in the asci. Pycnidia black, laminal, immersed, of the Dermatocarpon-type. Conidia subcylindrical, 3.5-5 x 1-1.5 µm. Photobiont chlorococcoid (Myrmecia. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a Mediterranean species recalling H. imbricatum but with much thinner and strongly divided squamules, found on base-rich soil over siliceous substrata in dry sites; hitherto known only from southern Europe (Italy, SE Spain, Balkan Peninsula).
Growth form: Squamulose
Substrata: soil, terricolous mosses, and plant debris