Parmelia ernstiae Feurer & A. Thell

    This species is very similar to Parmelia saxatilis to the point of often being confused with it, or considered as a variety or a form, and differs  by its lobes, grey-green when moist, greyish when dry, more or less indented, thallus surface usually devoid of pseudocyphellae (or scarce and inconspicuous), pruinose (almost tomentose), by its conical isidia mixted with minute foliate isidia (phyllidia). Lower surface dark brown to blackish with rhizines, simple or end-branched. Apothecia scarce, sessile, cup-shaped, 0.3-0.8 cm diam., disc concave, brown-orange, exciple pleated to ribbed, concolourous to the thallus. Ascospores simple, colourless, broadly ellipsoid, (13) 15-18 x (8) 9-12 (13) µm according to our measures. Cortex: K+ faint yellow, medulla: K+ yellow > red-orange, Pd+ golden yellow. Rare, on bark of trees in shaded situations (Fraxinus, Quercus,...). N.B. Following molecular analyses, the satus of this taxon was recently recognized as deserving the rank of species :

FEURER & THELL A. (2002). Parmelia ernstiae a new macrolichen from Germany. Mitteilungen des Instituts für Allgemeine Botanik. Hamburg. 30-32 : 49-60.

M. del C. MOLINA, A. CRESPO, O. BLANCO, H. T. LUMSCH, & D. L. HAWKSWORTH. (2004). Phylogenis relationships and species concepts in Parmelia s. str. (Parmeliaceae) inferred from nuclear ITS, rDNA and B-tubulin sequences. The Lichenologist 36 (1) : 37-54.*