New records of the occurrence of Megaleporinus macrocephalus () (Characiformes, Anostomidae) from the basins of the Itapecuru and Mearim rivers in Maranhão, Northeastern Brazil.

M S Almeida,E C Fraga,M H S Nascimento,F M Assega,M C Barros,J L O Birindelli,P S S Moraes

doi:10.1590/1519-6984.232868

Abstract

The "piaussu", Megaleporinus macrocephalus is an anostomatid fish species native to the basin of the Paraguay River, in the Pantanal biome of western Brazil. However, this species has now been recorded in a number of other drainages, including those of the upper Paraná, Uruguay, Jacuí, Doce, Mucuri, and Paraíba do Sulrivers. This study presents two new records of the occurrence of M. macrocephalus, in the basins of the Itapecuru and Mearim rivers in the state of Maranhão, in the Brazilian Northeast. The piaussu is a large-bodied fish of commercial interest that is widely raised on fish farms, and its occurrence in the Itapecuru and Mearim rivers is likely the result of individuals escaping from fish tanks when they overflow during the rainy season. Morphological analyses and sequences of the Cytochrome Oxidase Subunit I (COI) gene confirmed the taxonomic identification of the specimens as M. macrocephalus. The COI sequences were 99.66% similar to those of M. macrocephalus deposited in the BOLDSystems database. These records extend the known distribution of M. macrocephalus to the basins of the Itapecuru and Mearim rivers in the Brazilian Northeast, highlighting a new case of introduction of exotic fish species into Brazilian river basins.

Highlights

The family Anostomidae is currently composed of 149 valid species, distribuided in 15 genera (Fricke et al, 2020)
The present study provides the first report of the occurrence of M. macrocephalus in northeastern Brazil, in the Itapecuru and Mearim rivers, in the state of Maranhão
On the Mearim River, one M. macrocephalus specimen was collected on the lower course of the river at Laje dos Currais, in the municipality of São Mateus, during the flood season, while two specimen was obtained on the middle course of the river in the town of Pedreiras during the dry season

Summary

Introduction

The family Anostomidae is currently composed of 149 valid species, distribuided in 15 genera (Fricke et al, 2020). Species of the family are endemicthe Neotropical region, and a widely distributed from north of the Colombia to La Plata River, in Argentina (Garavello and Britski, 2003). The genus Leporinus Agassiz, 1829, is the most species-rich of Anostomidae (Burns et al, 2017). Garavello and Britski (1988) described Leporinus macrocephalus based on 15 specimens collected in the Paraguay River basin in Brazil. The species was recently transferred to Megaleporinus, a genus described in 2017 by Ramirez et al (2017), based on morphological, molecular, and cytogenetic data, including a unique system of ZZ/ZW sex chromosomes

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