Manual of the South American Diptera

South America is composite both in a geological and a biogeographic perspective. A “Neotropical region” was already recognized by Sclater (1858), while Gill (1885), Allen (1892), and Lydekker (1896) took the southern portion of South America as a separate biogeographic region, having similarities with New Zealand and Australia. Jeannel (1942) coined the term Archiplata for the South American temperate subregion, which with the rest of the austral temperate areas was collectively referred to as Paléantarctide.

South America has a complex vegetation structure with the forest biomes being the most well known. They comprise the Atlantic Forest, and the Amazon Forest (to which the Central American and Caribbean tropical forests are obviously connected). The ‘Amazon Forest’ is not a historical entity with some of its elements being more connected to external elements than to other Amazon elements.

The expression ‘open vegetation’ refers to a spectrum of biomes, mostly running from northeast to southwest in South America. The cerrado—a savana-like environment—is the most important one and occupies large expanses mostly in central Brazil with isolated spots in southern Brazil and within the Amazonian forest. The caatinga—a dry or semi-arid environment—occupies large portions in northeastern Brazil. More to the southwest, the pampas, a particular kind of grassland, occupy part of Argentina, Uruguay, Paraguay and southern Brazil. Southeastern Brazil has grassland biomes over rocky soil called rupestre fields, usually above 1,000 m elevation but also present in some rocky lowlands. Higher terrains along the Andes are also quite specialized in their fauna and flora, including the paramos in the northern part of the Andes (including some spots in Central America, northern Brazil, and southern Venezuela) and the Andean scrubs in Peru, Bolivia, and northern Argentina and Chile. Finally, the Patagonian steppes and the well-characterized Atacama Desert in northern Chile and southern Peru should be mentioned. Most of these open environments are rich in strong dipteran flyers, such as Tabanidae, Nemestrinidae, Acroceridae, Asilidae, Bombyliidae, and Therevidae, but have as well species of dozens of other families that have adapted. The diversity of these biomes remains largely understudied.

The Diptera elements in the southern temperate forests in South America have circum-Antarctic connections and are considerably well known. These are the dominant elements in temperate forests in Chile and southern Argentina, but they extend their distributions to the north along the Andes, reaching as far as Colombia and into areas of higher altitude in southern and southeastern Brazil.

Forest canopy corresponds to an environment with dipteran elements associated with open areas, and quite strongly contrasts to the dipteran fauna in shaded parts of forests. Modified Townes traps placed at the canopy collects dipterans typical of open vegetation, as tabanids, mydids, asilids, bombyliids, calyptrates, but also species associated to flowers, such as ulidiid and tephritid species, that cannot be collected otherwise.

An additional component in South America biodiversity is associated with aquatic environments. The tropical freshwater environments are highly diverse for the families of Tipulomorpha, Psychodidae, most families of the Culicomorpha, and Ephydridae, but also include elements of other families. Marine dipterans are less common but includes the chironomid genera Telmatogeton Schiner and Clunio Haliday, a number of dolichopodids, and acalyptrates, as canacids that breed in decaying algae on sandy beaches. Mangroves also have rich and specialized fauna of some families, especially dolichopodids.

(largely based on Amorim 2009)