A monograph of the genus Placomaronea is presented; all species described earlier are revised, a total of six species is recognized, and an identification key is presented. In addition to the three previously known species, P. candelarioides, P. lambii and P. mendozae, three new species are described: Placomaronea kaernefeltii is a large rosette-like species known from one locality in northernmost Chile; Placomaronea fuegiana is a bullate, areolate species described from Tierra del Fuego, Argentina; Placomaronea minima is a small, areolate to minutely lobate species described from Chile and Argentina, and is the first species of Placomaronea to be reported from the African continent. In a phylogenetic analysis of nuclear ITS rDNA, Placomaronea is shown to form a monophyletic group within the Candelariales.
