Solorina spongiosa (Ach.) Anzi
Scaly thallus 1-3 cm in diameter formed of a single cup-shaped scale with smooth, weakly sinuous, greenish-gray edges, enclosing the photobiont Coccomyxa, surrounded by a granular to warty gray belt of spongy consistency formed by a Nostoc, this belt of cyanobacteria that can sometimes extend in a carpet to form a pseudo-thallus. Apothecia usually single, 3-5 mm in diameter buried at the bottom of the cup, of which it can occupy almost the entire surface, concave disc, brown-black. Utriform asci with (2) 4 spores. Spores elliptical, brown, with a rough surface, 1-septate, 30-55 x 18-25 µm according to the literature, 35-54 x 19-25 µm according to our measurements. Mountain and alpine species found on soils and crevices in limestone regions covered with snow in winter.
N.B. Differs from Solorina bispora by its asci with (2) 4 spores and its Coccomyxa thallus almost entirely occupied by an apothecia.