[[Genus Plagioscion Gill]]

Introduction

The sciaenid genus Plagioscion Gill 1861 is endemic to South American fresh waters, where its members were originally distributed in the Río Magdalena, Río Amazonas, Río Orinoco, lower Río Paraná basins and rivers of the Guianas (Casatti, 2003). Members of the genus have also been introduced into the upper Río Paraná and Río São Francisco basins and in artificial reservoirs of northeastern Brazil. The monophyly of Plagioscion is supported by two characters (intercalar projecting downward and modified lateral-line scales [Sasaki, 1989]), and it is currently included in the subfamily Cynoscioninae. The systematics of Plagioscion is poorly understood, an unfortunate situation given the importance of the genus in subsistence and commercial fisheries. In this paper, the valid species of Plagioscion are revised and diagnosed, and an identification key is provided.