Gymnotus Linnaeus

William G. R. Crampton, Nathan R. Lovejoy & James S. Albert, 2003, Gymnotus ucamara: a new species of Neotropical electric fish from the Peruvian Amazon (Ostariophysi: Gymnotidae), with notes on ecology and electric organ discharges., Zootaxa 277, pp. 1-18 : 1-2

[[ Genus Gymnotus Linnaeus ]]

The weakly electric Neotropical fish genus Gymnotus has been the subject of several taxonomic studies in recent years (Mago-Leccia 1994; Albert & Miller 1995; Campos da Paz 1996; Campos da Paz & Costa 1996; Albert et al. 1999; Campos da Paz 2000; Albert 2001; Albert & Crampton 2001; Campos da Paz 2002). Until recently Gymnotus was recognized as the only genus in the family Gymnotidae. The monotypic genus Electrophorus Gill , comprising the single strongly electric species Electrophorus electricus (L.) was recently included in the Gymnotidae (Albert 2001).

Albert (2001) and Albert and Crampton (2001) summarized the diagnostic characters of Gymnotus . Albert and Miller (1995) and Albert (2001) recognized three species groups within the genus based on color pattern, body proportions and counts. These are the G. cylindricus , G. pantherinus , and G. carapo species-groups. The species composition and geographical range of these groups are summarized in Table 1. The G. cylindricus species-group is endemic to both Atlantic and Pacific drainages of Middle America and comprises just two species. The G. carapo species-group is endemic to South America and is represented by seven species distributed from the Pacific slope of Colombia to the Pampas of Argentina. The G. pantherinus species-group is represented by nine species with distributions from Panama to Paraguay. Species in the G. carapo species-group, including the new species described here, can be distinguished from species in the G. pantherinus and G. cylindricus species-groups by the possession of a clear or pale patch near the caudal end of the anal fin, and two (vs. one) laterosensory canal pores in the preopercular-mandibular series of the dorso-posterior portion of the preopercle. We use the above classification of Gymnotus as a basis for the differential diagnosis of the new species described in this report. There are currently 18 valid species of Gymnotus , of which thirteen are found in the Amazon basin. Several new species of Gymnotus have recently been discovered in the Brazilian portion of the Amazon basin (Albert & Crampton 2001; Campos da Paz 2002), including seven new species from whitewater floodplains or ‘ várzeas ’ along the Amazon River’s main stem (Albert & Crampton 2001). Here we describe a new species from várzea floodplains of the Rio Ucayali Basin in the Peruvian Amazon.