Genus Pterocnemia is a group of flightless birds native to South America. It is sometimes referred to as the rhea or nandu genus, with "nandu" being used in some regions while "rhea" is more commonly used in others. The genus includes three extant species: the lesser rhea, Darwin's rhea, and the greater rhea. In some countries, the Rhea genus is also known as Avestruz yareta, Suruvi, nandú, choique, and suri. The use of these synonyms depends on the region and the language. Regardless of their names, all species within the Genus Pterocnemia share similar features and adaptations to life on the South American plains.