This is a list of butterflies of the Amazon River basin and the Andes.
The Amazon River basin may be the most speciose region for butterflies. Nine countries have territory in the Amazon River basin or immediately adjoin this region: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname, and French Guiana. The Andes extend from north to south through seven South American countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. The fauna of the Andes is also diverse. Both regions have many endemic species. South America as a whole constitutes the Neotropical realm. Habitats in these two regions are very various and include Amazon rainforest, Atlantic forest, Llanos grasslands, Puna grassland and Valdivian temperate forests. Peru east of the Andes is regarded as the most important biodiversity hotspot in the world. The two regions (Amazon and Andes) are South America proper excluding the pampas plains of Uruguay and Paraguay which have a distinct butterfly fauna.
Isolation has led to the evolution of endemic higher taxa. Instances are Ithomiinae, Dismorphiinae, Phyciodina, Pyrrhopygini, Eumaeini (over 1,000 species), Pronophilina and Eudaminae. Endemic genera (among very many) include Morpho, Agrias, Prepona Caligo, Cithaerias, Catagramma, Parides, Hamadryas, Nessaea, Marpesia, Melanis Mesosemia, Symmachia, Evenus, Memphis, Pierella, and Astraptes. Other higher taxa are most speciose in the Neotropics, for instance Riodininae. Many species, notably Heliconius, are members of complex mimicry rings. Adaptive radiation has led to many species being geographically diverse. Examples are Consul fabius and Mechanitis lysimnia.
Notable entomologists associated with Neotropical butterflies are Jean-Baptiste Godart, Henry Walter Bates, William Chapman Hewitson, Hans Fruhstorfer, Otto Staudinger, Karl Jordan and Walter Rothschild, Anton Hermann Fassl, Hermann Burmeister, William Schaus, Eugène Le Moult, Richard Haensch, Gustav Weymer, Ferdinand Heinrich Hermann Strecker, Andrey Avinoff, Carlos Berg, and Vladimir Nabokov.
