Abstract
Orestias Valenciennes 1839 is a fish genus of the family Cyprinodontidae Gill, 1865, endemic to the Altiplano in the Andes range. The genus includes 45 species (44 valid and one species inquirenda) according to Eschmeyer & Fong (2013); more than half inhabit the Lake Titicaca basin (23 species). The rest of the species have been described from different Altiplano aquatic systems, from Lake Lacsha in the center of Peru to the Ascotán salt pan in northern Chile (9°S to 22°S) (Lauzanne 1982; Vila 2006; Vila et al. 2011). Due to the high species diversity, the genus Orestias has been used as a study model for speciation processes. Sympatric speciation has been proposed for Lake Titicaca (Baker et al. 2001), and allopatric speciation for the rest of its geographic distribution (Parker & Kornfield 1995).