Roccella tinctoria DC  Taxon Méditerranée-Corse

    Thallus fruticose, shrubby and forming small rounded tufts, 3-5 cm tall and 5-10 cm across, branches more or less terete, apices pointed, 1-3 mm diam., surface smooth most often with soralia, rounded, pustulose, lens-shaped, becoming globose, farinose and whitish, overall colour of branches: grey-reddish, grey with purple tinge, grey-brownish, etc. Apothecia very scarce, 1-2 mm diam., black. Ascospores 3-septate, 23-27 x 6-8 µm. Photobiont: Trentepohlia. Cortex and medulla K+/- yellow, C+ bright carmine. Rare, saxicolous, thermophiles, Macaronesian, on rock vertical walls of West coast of Corsica. N.B. Very similar to  Roccella phycopsis but the latter is not C+ carmine. N.B. This species has been reported in Ouessant island, Finistère, Brittany, but some differences are found and the climatic conditions are far apart, see  Roccella tinctoria Atlantic-Ouessant and Roccella tinctoria Taxon Atlantique-Manche.

Tehler A., Dahlkild A., Eldenäs P. & Feige G.B. 2004. The phylogeny and taxonomy of Macaronesian, European and Mediterranean Roccella (Roccellacea, Arthoniales). Acta Univ. Ups. Symb. Bot. Ups. 34:1, 405-428.