Illustrated identification key for Characidae (Characiformes) fishes from a protected area and vicinity, upper Rio Paraná, Brazil

Abstract

Characidae is the most diverse family of Neotropical ichthyofauna and has a conservative external morphology, making the identification process difficult without comparative material. Producing identification materials aimed at non-specialists is necessary to accelerate research on the ichthyofauna, contribute to its preservation, and assist in training human resources. This work aimed to elaborate an illustrated dichotomous identification key for the fish of this family around the protected area Biological Refuge of Santa Helena and adjacent rivers, upper Rio Paraná basin, Brazil-Paraguay border. This region was inventoried quarterly from November 2017 to November 2019, and additional collections occurred from 2019 to 2022. For the elaboration of the identification key, the fish were divided into increasingly less inclusive groups based on the presence, absence, or state of morphological characteristics. These characteristics were photographed under a stereoscopic microscope, and auxiliary figures for the identification key were provided. This work includes 26 species, including three notable additions to the region's existing identification guides: Deuterodon luetkenii, Serrapinnus kriegi, and Psalidodon sp. The latter represents a possible new species. It also discusses taxonomic issues and compares similar species.