Heterodermia obscurata  

Thallus 3-8 cm diam., rather variable in form, often with neat rosettes or more rarely widely spreading. Lobes 2-4 mm wide, ± flat, contiguous, not ascending but sometimes raised at the tips, ± palmately branched and sometimes appearing fan-shaped. Upper surface ivory white to pale grey, smooth or rarely with abundant minute, crowded, granular lobes at the centre of the thallus. Soralia lip-shaped, on recurved apices of the lobes, the soredia coarse and ± concolorous with the thallus. Marginal cilia 1-3 (-7) mm in length, short and dark. Lower surface non-corticate, matt, minutely fibrous, white with pale yellow to orange or dark ochraceous spots sometimes covering most of the undersurface.
Anamorph: rarely reported; conidiomata pycnidia, with conidia 4-5 x ca 1 µm in size.
Teleomorph: ascomata apothecia, very rare; disc brown-black with a coarsely crenulate or sorediate thalline exciple. Ascospores 21-31 × 12-17 μm.
Chemistry: upper surface C–, K± yellow, KC–, Pd– (zeorin, atranorin), pigment K+purple.

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