Phylogenetic and revisionary taxonomic studies of the banded knifefishes Gymnotus (Teleostei, Ostariophysi, Gymnotiformes) with descriptions of fourteen new species

Gymnotinae (new subfamily) is a species-rich clade of Neotropical electric fishes (Teleostei, Gymnotiformes) that occupies most freshwater habitats in the lowland Neotropics excluding deep river channels, from southern Mexico to northern Argentina. Gymnotinae as recognized here includes 51 species in two genera (Gymnotus new combination, PARAGYM gen. nov.), and exhibits highest diversity in the lowlands of Western Amazonia from where 18 species (35% of the total) are known. Gymnotine species exhibit considerable morphological and ecological diversity, ranging in mature body size over an order of magnitude (c. 8-100 cm). Our understanding of the high diversity of this group only became apparent during the past 15 years with technical advances in measuring electric discharges, as well as chromosomal and genetic diversity. This study provides: 1) an alpha taxonomic revision of the Gymnotinae, with descriptions and differential diagnoses for 37 previously recognized species, and descriptions and diagnoses for 14 new species and six new subspecies using external and osteological characters; 2) identification keys for each major hydrogeographic basin; 3) phylogenetic analysis including all newly described species based on 105 morphological characters and multiple coding schemes, with results compared to those of previous hypotheses using morphological and molecular data; 4) re-describes and clarifies the status of the enigmatic tuvirão (G. inaequilabiatus) using 3D reconstructions from computed tomography of the holotype to establish its phylogenetic position; 5) uses multivariate statistical analysis of morphometric and meristic data to recognize six subspecies within the geographically widespread paraspecies G. carapo, and to evaluate the use of the subspecies rank as a taxonomic tool for recognizing significant, but not disagnostic, infraspecific variation.