Dermatocarpon intestiniforme (Körb.) Hasse ss. Körber, Poelt, Clauzade & Roux...

    Thallus foliose, composed of a single lobe but looking like a thallus made of numerous imbricate lobes, tightly attached to the substratum by several holdfasts, lobes convex and wavy, upper surface seemingly pruinose due to aeriferous hyphae within the cortex, greyish, brown-greyish when moist, lower surface smooth to slightly veined, without rhizine but with holdfasts. Perithecia numerous, 0.2-0.3 mm diam., more or less immersed, blackish, perithecia numerous, rather similar, smaller. Ascospores colorlourless, simple, sub-globose to globose, 6-10 x 5-7 µm. Photobiont: green algae. Chemical spot tests negative but medulla I+. Rare, montane, on calcareous rock sloping walls. See Dermatocarpon complicatum rather similar but growing on siliceous rocks, with larger and narrower ascospores. See also  Dermatocarpon luridum that grows on periodically flooded rocks in rivers and streams and with medulla I+ red.