A new miniature species of Priocharax (Characiformes: Characidae) from the upper rio Ipixuna, Purus drainage, Brazil

Camila da Silva de Souza,Claudio Oliveira,George Mendes Taliaferro Mattox,Mônica Toledo-Piza

doi:10.1590/1982-0224-2021-0048

Abstract

Abstract A new species of miniature fish of the characid genus Priocharax is described from a small lake near the rio Ipixuna, rio Purus drainage, Amazonas State, Brazil. It is distinguished from all congeners except P. pygmaeus by the lower number of teeth on the maxilla and dentary. It differs from P. pygmaeus by the presence of two postcleithra and 22–27 branched anal-fin rays (vs absence and 19–22). The new species is further distinguished from other species of Priocharax by a combination of characters involving the number of pelvic-fin rays and branched anal-fin rays, the number of postcleithra, the shape of postcleithrum 3, and the absence of the claustrum. Molecular evidence based on COI sequences of all valid species of Priocharax also corroborates the validity of this new species.

Highlights

Priocharax Weitzman & Vari, 1987 is a genus of characid fishes from the Amazon and Orinoco basins that currently includes four species, all of them miniature
Supraneurals, teeth, gill-rakers, procurrent caudal-fin rays, and information about osteological characters were obtained from six specimens cleared and double stained for cartilage and bone following the protocol of Taylor, Van Dyke (1985)
Overall and pairwise genetic distances were estimated based on the Kimura 2-parameter model (K2P) + Gamma using MEGA X and the order of groups was based on the ABGD and Poisson Tree Processes (PTP) results

Summary

INTRODUCTION

Priocharax Weitzman & Vari, 1987 is a genus of characid fishes from the Amazon and Orinoco basins that currently includes four species, all of them miniature. Priocharax ariel Weitzman & Vari, 1987 and P. pygmaeus Weitzman & Vari, 1987 were both described with the genus from the upper reaches of the ríos Orinoco and Negro in Venezuela and from the upper río Amazonas in Letícia, Colombia, respectively (Weitzman, Vari, 1987). Almost 30 years later, Priocharax nanus Toledo-Piza, Mattox & Britz, 2014 was described from the surroundings of Santa Isabel do Rio Negro in the middle rio Negro, Brazil. Priocharax varii Mattox, Souza, Toledo-Piza, Britz & Oliveira, 2020 was described from the rio Jamari, a tributary of the Madeira system, in Brazil. In a recent expedition to the rio Ipixuna, an affluent of the Purus drainage, specimens of a new species were sampled which is described

MATERIAL AND METHODS

RESULTS

DISCUSSION