Umbilicaria nylanderiana

Umbilicaria nylanderiana is a species of foliose lichen in the family Umbilicariaceae. It typically appears as a single, rigid disc attached to rock surfaces. First described in 1927, it can grow up to 6 cm (2.4 in) across and is characterised by its dark brown to grey upper surface with dense, rounded ridges, and a black lower surface. The species is found worldwide on boulders and cliffs in alpine regions, including Europe, North and South America, and parts of maritime Antarctica. It can be distinguished from similar-looking species by its production of specialised reproductive structures called thalloconidia, which appear as dark oval cells covering most of its lower surface.