Diplotomma venustum Körb. ss. auct. gall.
Diplotomma epipolium var. reagens J. Steiner
Buellia venusta (Korb.) Lettau
Thallus crustose, relatively thick (especially in the center), well defined, smooth surface, areolate, chalk white, dirty white, sometimes with ocher-red or orange spots. Apothecia numerous, scattered throughout the thallus, 0.5-1.5 mm in diameter, not very prominent; at the beginning flat then convex at the end, powdered with whitish at the beginning and sometimes surrounded by a "collar" of fragments of the thallus, black. Spores elliptical, somewhat kidney-shaped, brown, 16-22 x 7-9 µm. Photobiont: chlorococcoid. Medulla: C-, K+ pale yellow then reddish (especially in places already ocher-pink whose coloring is accentuated), P-, I-. Mediterranean saxicolous species coming on the hard limestone rocks very sunny. Parasite, at least initially, of Protoparmelia muralis var. versicolor. Species very similar (if not identical!) Of Diplotomma hedinii which is K- and less thermophilic.
N.B. This species is named here in the sense of the French authors, some European authors considering that it is a simple form of Diplotomma hedinii.