A viewpoint of Patagonian Biogeography from the Ceratopogonidae case (Insecta: Diptera)

SPINELLI GR; MUZÓN J

BIOGEOGRAPHICA (PARIS)

Año: 2000 vol. 76 p. 125 - 132

1165-6638

Some of the current accepted ideas about the origin and settlement of the taxa inhabiting the patagonian steppe are discussed from data on recent collections of small-sized midges of the family Ceratopogonidae (Diptera: Nematocera). The findings in the Valcheta stream basin, Sierra Cuadrada plateau and valley of the river Pinturas of species belonging to genera of undoubted transantarctic origin (Paradasyhelea and Macrurohelea) suggest that current biogeographic schemes highly simplify the Natural History of Patagonia, postulating a clear distinction between the two main biomas: forest, with a biota characterized by a high degree of endemicity and closely related to fauna and flora of Australia, New Zealand and neighboring islands, and steppe, with a depauperate guyano-brazilic biota. Despite the strong desertification process suffered by the area after the last glaciation, the surveyed steppe localities could represent area with persistent favourable environmental conditions, where the manteinance of healthy vicariant populations of species belonging to ancestral taxa could have been possible. Desertification is the herein postulated vicariant event, and a closer relationship between the above mentioned biomas is suggested considering records gathered from taxa inhabiting aquatic ecosystems in the steppe.