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. A species with mountain tendencies, rare in our region, growing on the acidic bark or bare wood of conifers, particularly Scots pines (Pinus sylvestris).

_ Not to be confused with Parmeliopsis ambigua that shares the same habitat, is R-, and has soralia.