Lepra aspergilla (Ach.) Hafellner =Pertusaria aspergilla (Ach.) J. R. Laundon

    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 Lepra excludens,  K+ yellow > red.  Lepra leucosora, possibly a synonym, differs by its Pd+ orange reaction and not red (see picture) though intermediate specimen may be found.