Pertusaria aspergilla (Ach.) J. R. Laundon
Pertusaria dealbescens auct. non Erichsen
Pertusaria leucosora auct. non Nyl.
Lepra aspergilla (Ach.) Hafellner
Thallus rather thin, cracked, areolate, pale or dark grey, covered with soralia, 0.5-1 mm, more or less convex or rounded, punctiform, whitish, and with rare cylindrical soredia, white, prothallus sometimes absent or inconspicuous, grey-whitish. Apothecia unknown. Thallus: C-, K+ dull yellow to yellow-brown, KC+ yellow-orange, Pd+ rusty-red to bright red. Not especially maritime but able to grow on siliceous rocks near the seashore and common on rocks in the Monts d'Arrée. Not to be confused with Pertusaria lactea which is Pd- and C+ red and with Pertusaria excludens, K+ yellow > red. Pertusaria leucosora, possibly a synonym, differs by its Pd+ orange reaction and not orange (see picture) though intermediate specimen may be found.