Lecidea fuscoatra

Lecidea fuscoatra is a species of saxicolous (rock-dwelling) crustose lichen in the family Lecideaceae. This widespread species is found across Europe, North America, North Africa, and Asia. First described by Carl Linnaeus in 1753, it forms a thin crust that breaks into small, shiny, tile-like patches ranging from whitish grey to pale brown, typically outlined by a black border of fungal tissue. The lichen produces small black disc-shaped fruiting bodies that are often nestled between the crustal patches and contain eight colourless ascospores per spore sac. It grows primarily on acidic rocks such as granite and sandstone, and is particularly common in northern boreal regions, though it also readily colonises worked stone structures in coastal areas. The species can be distinguished from similar-looking lichens by its distinctive areolate (tile-like) thallus structure that forms discrete patches from early growth, and by its positive reaction to the C spot test due to the presence of gyrophoric acid.