Notes on the phylogeny of the American Penaeus shrimps (Decapoda: Dendrobranchiata: Penaeidae)

Abstract

A cladistic analysis was performed to determine genealogical relationships among subgenera of the shrimp genus Penaeus and for species in the American subgenera Farfantepenaeus and Litopenaeus. Using a combination of genital and somatic characters, Penaeus subgenera were found to exhibit the following pattern of relationships: [Litopenaeus [Fenneropenaeus [Penaeus s.s. [Melicertus - Farfantepenaeus - Marsupenaeus ]]]]. Four genital synapomorphies divide Farfantepenaeus into 2 species groups: a P. (F.) brasiliensis complex consisting of P. (F.) brasiliensis, P. (F.) californiensis, P. (F. ) duorarum, and P. (F.) notialis and a P. (F.) aztecus complex comprised of P. (F.) aztecus, P. (F.) brevirostris, P. (F.) paulensis, and P. (F.) subtHis. Additional characters permitted a phylogenetic hypothesis to be developed for Farfantepenaeus taxa. Fortytwo genital character states revealed the species in the subgenus Litopenaeus to have the following relationships: [P. (L.) vannamei [P. (L.) occidentalis [P. (L.) stylirostris [P. (L.) schmitti - P. (L.) setiferus]]]]. Evolutionary patterns in the genus are discussed.