Nimisia deusta, based on Parmelia enteromorpha var. deusta, is shown to be the correct name for the species currently known as N. fuegiae. Original material collected by J. D. Hooker in 1842, and collections made by Henry Imshaug between 1968 and 1971, have shown that the species is more widely distributed than previously reported, being known throughout the southern tip of South America (Argentina: Isla Grande de Tierra del Fuego, Isla de los Estados; Chile: Cape Horn Islands; Falkland Islands), that it has a uniform secondary metabolite chemistry of fumarprotocetraric acid in the upper medulla (not lacking lichen substances as previously reported), and that it is not uniformly black but has a partly pale brown upper cortex.