A new species of Penaeus (Crustacea : Penaeidae) revealed by allozyme and cytochrome oxidase I analyses

Penaeid shrimps comprise an important portion of the world's industrial fis heries and mariculture. In the Southwest Atlantic, Penaeus (Farfantepenaeus ) subtilis, P. (F.) paulensis, P. (F.) brasiliensis and P. (Litopenaeus) sc hmitti are the most important commercially exploited species. Despite their high commercial value, there is little information available on the differ ent aspects of their biology or genetics and almost no data on stock struct ure. Also, the taxonomic status of P. subtilis populations in relation to P . paulensis and their geographic ranges have been recently questioned. In t his paper we used both nuclear (allozymes) and mitochondrial (cytochrome ox idase subunit 1) data to compare species of south-western Atlantic penaeids and to estimate their phylogenetic relationships. We could readily discrim inate among the four main Brazilian penaeid species and detected a fifth, n ew, species of Penaeus. This new species corresponded to one of the describ ed morphotypes of P. subtilis. Based on these analyses, the geographic rang es of P. subtilis and P. paulensis were clarified. Our data also support th e conclusion of Baldwin ct al. (1998) that the subgenus Farfantepenaeus is polyphyletic.