Parmelia discordans Nyl.

    Thallus foliose, 5-10 cm across, loosely attached to the substratum, lobes small, 0.5-2 mm wide, imbricate, breakable, slightly and lengthways folded, upper surface glossy, evenly brown to dark brown with scarce pseudocyphellae, mostly marginal, not forming a network, lower surface blackish with simple or branched rhizines. Apothecia rare, sessile and cup-shaped, 0.5-0.8 mm diam., disc dark brown, concave to flat, exciple  irregular, paler. Ascospores ellipsoid, 10-15 x 7-9 µm. Photobiont: green algae. Cortex: K+/- yellow; medulla: C-, K-, KC+/- purple, Pd+ yellow-orange to rusty. Rare in our prospection area, montane and northern, on rock ridges in the Arrée Mounts and on exposed rocks of cliffs of capes and heads in Finistère. May be found on tree barks according to the literature. N.B. This species is rather similar to Parmelia omphalodes and was subject to various interpretations. The specimen presented here, collected in the Finistère, might well be an oceanic form of Parmelia omphalodes and this explains why we also present  other specimen sampled in Sweden and reported as representative of Parmelia discordans ss. auct. nord.*