Lepra leucosora (Nyl.) Hafellner =Pertusaria leucosora Nyl.

    Thallus crustose, usually rather circular, to 10 cm diam., rather thick, areolate, greyish, pale to dark grey, surface uneven with warts, 0.5-1.5 mm diam., soralia abundant, rounded, clustered towards the center, whitish, soredia indistinctly granulose, whitish, margin with a zonate structure but without visible prothallus. Apothecia unknown. Thallus, cortex and medulla: C-, K-, KC+/-yellowish to yellow-reddish, Pd +/- yellow > orange to orange-reddish (notably soralia). On alkaline rocks near the seashore: basalts, serpentine, but also on weakly acid rocks inland (schist ridges). N.B. May be very close to (or even synonym according to some authors) Lepra aspergilla but different by its chemical reactions ( more orange)  and the rounded soralia. N.B. This species is higly variable, notably considering its chemical properties, and subjected to various interpretations. It probably encompasses several taxa; to British authors, limited to the English Channel islands and to Cornwall coastal regions see Lepra leucosora ss. auct. brit.; French authors however tends towards considering  it is a ubiquist species... Additional investigations are needed to clarify this specific point.