Abstract

In the Southwestern Atlantic Ocean, several described species of Clupeiformes overlap their geographical distribution in the coastal areas from Rio Grande do Sul (Southern Brazil) to Bahía Blanca (Argentina) and the Río de la Plata estuary. Larvae and juveniles of the SW Atlantic menhaden Brevoortia aurea are very difficult to discriminate from those of other clupeids belonging to the genera Platanichthys andRamnogaster inhabiting the same environments. Here we implemented phylogenetic analyses based on mitochondrial cytochrome b sequences and morphometric and osteological studies to achieve unambiguous species recognition in different ontogenetic stages of six endemic species of Clupeiformes from the Southwestern Atlantic Ocean. All phylogenetic analyses based on the cytochrome b gene yielded a robust support to the existence of highly structured and monophyletic groups conforming clupeiforms taxa. These monophyletic entities were consistent with major groups accessed through the first two principal components (PCs) from morphometric variation among taxa. Both approaches resulted in accurated and complementary tools for the individual assignment in clades and groups within Clupeiformes during different ontogenetic stages in their life cycle. The detection of species-specific spawning and nursery areas through accurated methodological approaches of identification constitute a prerequisite for a sustainable management in pelagic fisheries.

Key words: Estuarine, clupeiformes, identification, morphology, cytochrome b.