Xanthoparmelia conspersa (Ehrh. ex Ach.) Hale. Taxon Atlantique.

   Thallus foliose, forming large rosettes, up to 15-20 cm diam., made of divided and radiating lobes, ±3 mm wide,upper surface isidiate, isidia mostly numerous, cylindrical and coralloid, grey-greenish, yellow-grey, lower surface jet-black, with short, simple black rhizines, up to the margin. In general fertile with apothecia sessile, to 1 cm diam., disc brown-red, thalline exciple thin, crenulate, occasionally isidiate just like the lower part of the apothecia. Ascospores simple, ellipsoid, colourless, 6-10 x 4-5 µm. Photobiont: trebouxioide. Cortex : K-. Medullae : C-, K+ yellow-orange, KC+ red-orange, Pd+ orange. Species not especially maritime but very frequent on siliceous rocks in well-lit of the aerohaline zone, also in land on walls or rocks, also frequent on slate roofs by the sea. In case of narrow lobes and absence of isidia, think of the group of Xanthoparmelia stenophylla and also if total absence of isidia and appearance of Xanthoparmelia conspersa to Xanthoparmelia conspersa forma Cf.; if the medulla is K + red and isidia globose, see Xanthoparmelia tinctina.

N.B. Very variable taxon of which many forms, varieties or species have been described, see Xanthoparmelia conspersa f.orma, for the forms with particularly well developed isidia and Xanthoria conspersa taxon de Méditeranée.