Phylogenetic relationships and evolutionary history of the shrimp genus Penaeus s.l. derived from mitochondrial DNA.

Mitochondrial DNA sequences were used to reconstruct the phylogeny of the Penaeus s.l. genus of marine shrimp. This phylogeny was used to test the validity of hypotheses on the species groupings, in particular the subgenus/genus subdivision, and on the species' evolutionary history. Newly derived sequences of both 16S rRNA and COI genes from 19 species of Penaeus s.l. and one outgroup were combined with previous sequences from seven additional species to allow analysis of 26 of the 28 recognised (or nominated) species. Phylogenetic analyses do not support the validity of all the previously created six subgenera (or genera) but provide evidence for division of the genus into two previously unrecognised clades (Melicertus+Marsupenaeus and Penaeus s.s.+Fenneropenaeus+Farfantepenaeus+Litopenaeus). A key conclusion from a previous molecular study, that the subgenera Farfantepenaeus and Litopenaeus are paraphyletic, was rejected. The molecular data support an Indo-West Pacific origin of the genus, with a single relatively recent colonisation of the Western Hemisphere, and subsequent subdivision into two clades prior to the emergence of the Panamanian isthmus.