Roccella maderensis (J. Steiner) Follmann

    Thallus fruticose, shrubby, usually pendent, 10-20 long, arising from a single holdfast, outer edge brown to dark-brown, inner side withish, branches strap-shaped, more or less flattened, apices scythe-shaped, surface minutely rugose, overall colour pale greyish to pale grey-brownish without distinct purple tinge, numerous verrucose or farinose soralia, whitish. Cortex with palissade plectenchyma (perpendicular hyphae, anticlinally arranged). Apothecia very scarce. Ascospores fusiform, straight or slightly bent, 3-septate, 20-27 x 5-7 µm. Thallus cortex: K- (branch apices and soralia often K+ pink to pale red), C+ red (possibly pale), soralia, C+ red (N.B. Reactions rather variable. Here, only the most frequent are mentioned). Thermophile, on coastal rocks, notably vertical walls in the South of Portugal and Mararonesian Islands. Very close to Roccella fuciformis and difficult to distinguish to the naked eyes. The latter has soralia C+ red and cortex K+ yellow (lepraric acid) and overall colour with purple tinge. N.B.  Roccella allorgei has similar reactions to Roccella maderensis but branch apices are more terete.

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.