Gymnotidae, Rafinesque, 1815

Júnior, Horácio Ferreira Júlio, Tós, Claudenice Dei, Agostinho, Ângelo Antonio & Pavanelli, Carla Simone, 2009, A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin, Neotropical Ichthyology 7 (4), pp. 709-718 : 714

Gymnotidae

The only gymnotid genus recorded in the upper rio Paraná basin is Gymnotus , monophyletic and the most diverse and widespread of South American electric fishes ( Fernandes et al., 2005), with a single species previously found in this basin: G. carapo . Electrobiological, cytogenetic and molecular studies have shown that Gymnotus currently encompasses numerous different species throughout the Neotropical region, some of which are still undescribed ( Campos-da-Paz, 2003). Currently, five Gymnotus species are found in the upper rio Paraná: G. inaequilabiatus , G. pantanal , G. paraguensis , G. sylvius and G. pantherinus . The first was described from some imprecise sites, although the type locality has been indicated as the La Plata River . Several individuals previously identified as G. carapo in the whole rio Paraná basin, including the upper, are now attributed to G. inaequilabiatus . All Gymnotus species are frequently used as live bait by anglers, which might cause releases between basins by ill-informed fishers. Graça & Pavanelli (2007) have considered this possibility to justify the presence of G. pantanal and G. paraguensis in the upper Paraná in addition to the Itaipu impoundment. However, Langeani et al. (2007) consider the former as native species in the upper Paraná basin, attributing to the Itaipu impoundment only the presence of G. paraguensis in this ecoregion. Some Gymnotus species are presently abundant in the upper rio Paraná, mostly in lentic environments. However, due to misidentifications and further introductions, their genuine origin in that region remains uncertain.