Populations of <i>Characidium rachovii</i> (<i>Crenuchidae: Characidiinae</i>) with reduction of the adipose fin from Argentina and a Southernmost record of <i>C. occidentale</i>

Abstract

The objective of this note is to report on populations of Characidium rachovii with reduction and absence of the adipose fin from Salí-Dulce and Paraná River basins, Argentina. In addition, we make considerations about the use of this character as diagnostic at the alpha level and mention the occurrence of Characidium occidentale Buckup & Reis in the Lower Uruguay River basin. C. occidentale, was described by Buckup & Reis in 1997 for a tributary of the Uruguay River, in Brazil and we include the first report from the Chirimay Miní stream, a tributary of the Uruguay River in the Province of Misiones, Argentine.