Imshaugia aleurites (Ach.) S. L. F. Meyer

    Thallus foliose, forming small rosettes, < 5 cm diam., tightly appressed, lobes 1-3 mm wide, apices more or less indented, upper surface bright pale grey, pale grey-greenish, covered from the center with cylindrical or (seldom) coralloid isidia, tip eroded, greyish, dark greyish possibly with spots tinged grey-bluish or grey-pinkish, lower surface whitish to pale ochre with white, simple rhizines. Apothecia rare, 1-3 mm diam., disc flat, brown-red, exciple isidiate. Photobiont: Chlorococcoid. Ascospores ellipsoid, 6-9 x 5-6 µm. Cortex : K+ yellow > red-orange ; Medullae : C-, K+ yellow, KC-, Pd+ vermilion-red. Rare in our region, not especially maritime, on acid bark of trees, notably Pinus sylvestris exposed to the South. Not to be confused with Parmeliopsis ambigua that shares the same habitat, is R-, and has soralia.*