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.

_ Very variable taxon of which many forms, varieties or species have been described:

_ If the medulla is K+ red and the isidia globose see Xanthoparmelia tinctina.

_ See Xanthoparmelia conspersa forma corallina for forms with particularly well developed isidia and Xanthoparmelia conspersa Mediterranean taxon for Mediterranean forms.

N.B. In the absence of isidia think of:

_ The group of Xanthoparmelia stenophylla with narrow lobes arranged without orientation.

_ If very similar to Xanthoparmelia conspersa, but without isidia and with pycnidia, mainly on coastal rocks, see Xanthoparmelia cumberlandia.