Parmeliella triptophylla (Ach.) Müll. Arg.

    Thallus foliose, more or less rosette-forming, 5-10 cm diam., composed of minute squamules, <1 mm, slightly indented towards margin, margin sometimes upturned, grey-brownish, grey-olive, lead-grey, hypothallus conspicuous, wide and exceeding thallus rim, black, blue-black; covered, sometimes almost entirely with terete or digitate, erect isidia, greyish, grey-olive, mixed with minute pale grey lobules; overall appearence dark. Apothecia rare, 1 mm diam. disc flat, brown-red turning dark brown, proper exciple paler. Ascospores simple, colourless, broadly ellipsoid, 10-17 x 5-8 µm. Photobiont: Nostoc. Chemical spot tests negative. Rare in our prospection area, on mossy deciduous tree trunks in oceanic woodlands. N.B. Some morphotypes of Pannaria conoplea might be confusing but the overall appearence is much more blue. See also Parmeliella testacea of which squamules are larger and without prothallus at the edge.