Description of a new species of glass knifefish genus Eigenmannia (Gymnotiformes: Sternopygidae) from the rio Negro basin, Brazil

Abstract

A new species of Eigenmannia is described from the rio Negro basin, Brazil, based on both morphological and molecular datasets. It is distinguished from all congeners by the following combination of characters: subterminal mouth, absence of lateral-line stripe present, eye diameter corresponding to 22.0–29.3% of head length, ii,14–17 pectoral-fin rays, 185–225 anal-fin rays, 21–27 premaxillary teeth, 11–16 dentary teeth, 4–8 endopterygoid teeth, and basibranchial 1 unossified. Additionally, cytochrome oxidase I gene sequences were obtained from four samples to test the congruence between molecular and morphological datasets, employing three molecular species delimitation analyses: ASAP (Assemble Species by Automatic Partitioning), PTP (Poisson tree processes), and bPTP (Bayesian Poisson tree processes). ASAP and PTP analyses recovered the new species as a unique MOTU (molecular operational taxonomical unit), whereas the bPTP estimated three MOTU’s for this lineage. The new species also present significant genetic divergence from its congeners, ranging from 8.7 to 17.3%. Inconsistences between molecular species delimitation analyses, the phylogenetic implications of the presence of large eyes and the diversity of Eigenmannia in the rio Negro basin are discussed.

Keywords:
Biodiversity; Eigenmannia macrops; Electric fishes; Integrative taxonomy; Molecular species delimitation