Rinodina atrocinerea (Hook.) Körb.
Rinodina aspersa subsp. atrocinerea (Hook.) Cl. Roux
Thallus crustose, rather thin, smooth, markedly areolate, areoles angular, 0.5-2 mm across, flat, whitish to pale grey, ash grey, pale grey-bluish, pale grey-brownish, prothallus conspicuous, visible between areoles, margin potentially fimbriate, black. Apothecia 0.2-0.8 mm diam., innate becoming more or less sessile, disc flat to slightly convex, dark brown to black, exciple persistent, thin, concolourous to the thallus. Ascospores brown, broadly ovoid, apices more or less hemispherical, 1-septate, 16-21 x 9-14 µm. Pycnidia sometimes abundant. Photobiont: Trebouxia. Cortex : C+ faint red, K+ yellow, Pd+ yellow. Maritime trends, rare (ecotype?), on siliceous rocks, notably granite. See also Rinodina aspersa s.l. forma littoral intermediate and Rinodina aspersa subsp. aspersa which is sorediate.
N.B. This species share the same chemical reactions profile as Rinodina aspersa subsp. aspersa and some authors rank it as subspecies: Rinodina aspersa subsp. atrocinerea but here, considering its peculiar habitat and aspect, we decided to keep the rank of species until additional research clarifies this issue