Dermatocarpon complicatum (Lightf.) W. Mann
Dermatocarpon luridum var. decipiens auct.
Dermatocarpon miniatum var. complicatissimum
Dermatocarpon aquaticum var. decipiens auct.
Thallus foliose, rosette-shaped, 3-10 cm diam., composed of a single large squame with numerous lobes, tightly appressed, attached by several clustered holdfasts, lobes 5-12 mm wide, intertwined, margin more or less upturned, upper surface usually pruinose, grey-whitish, pale grey, pale grey brownish, not turning green when moist, lower surface dark brown, brown-blackish with holdfasts but without rhizines. Perithecia completely immersed, ostiole visible only as black dots. Pycnidia abundant. Ascci clavate, 8-spored, 60-75 x 15-20 µm according to our measures. Ascospores ellipsoid, simple, colourless, 11-15 x 5-7 µm selon according to literature, 13-16 (18) x 5-8 µm according to our measures. Photobiont: Myrmecia and Protococcus. Medulla: I-. Saxicolous, montane, on sloping and vertical walls of acid and siliceous rocks, notably in areas subjected to water drainage. Dermatocarpon intestiniforme is very similar, shares a similar habitat but on calcareous rocks (smaller and rounded ascospores). See also Dermatocarpon luridum that grows on rocks of regularly flooded banks of rivers, greener and with medulla I+ 'Porto' red.