Lepra albescens (Huds.) Hafellner morpho albescens forme corticole.  

 

=Pertusaria albescens (Huds.) Choisy & Werner var. albescens

    Thallus crustose, thin to moderately thick, slightly cracked, whitish when dry, grey-greenish to greenish when moist, distinctly delimited, margin poorly zoned, thallus covered with large, rounded soralia, 1-4 mm diam., typically flat and concave with a conspicuous margin (almost apothecia-like), hosting granular soredia, pale grey-whitish, whitish. Apothecia very rare, 3-4 at the top of a wart. Ascii 1-2-spored. Ascospores 170-300 x 50-115 µm. Soralia: C-, K-, KC-, Pd-. Not especially maritime, on bark of trees, mostly aligned trees along roads or in orchards or in open woodlands, more rarely on mossy rocks, see: Lepra albescens morpho albescens forme saxicole. Not to be confused  with Lepra amara of which the soralia are globose and markedly bitter and Ochrolechia turneri and especially of Ochrolechia microstictoides infertile of which the soralia are C+ yellow.

N.B. Pertusaria albescens var. corallina (Zahlbr.) Laundon  differs from the canonical type by its verrucose and nodulose soralia, its minute isidia more or less coralloid and potentially covering the whole thallus and its roundel-like zoned margin.