Phylogeny of the Infraorder Caridea Based on Mitochondrial and Nuclear Genes (Crustacea: Decapoda)

Shrimps of the infraorder Caridea occur commonly throughout marine and freshwater habitats. De-spite general knowledge of the group, phylogenetic relationships within the infraorder remain poorly known. The few studies that have focused specifically on the classification and evolutionary history within the Caridea have relied entirely on morphological characters and suggest conflicting phylo-genetic relationships. Robust molecular analysis is required to test current hypotheses. We present the first comprehensive molecular phylogeny of the group, combining nuclear and mitochondrial gene sequences, to evaluate the relationships among 14 superfamilies and 30 families. Bayesian and likelihood analyses were conducted on a concatenated 18S/16S alignment composed of 1835 basepairs. Results indicated no evidence contrary to hypotheses of monophyly within the families Alpheidae, Processidae, and Alvinocarididae. Ogyrididae is resolved as a sister clade to the Alphei-dae, as has been previously suggested. Our findings raise questions as to the systematic placement of the Procarididae within Caridea and suggest polyphyletic and paraphyletic relationships among genera within the families Atyidae, Pasiphaeidae, Oplophoridae, Hippolytidae, Gnathophyllidae, and Palaemonidae, as currently defined. Our results in some cases confirm and in others reject placements of controversial taxa within higher-level phylogeny and provide new insights for classi-fications within the Caridea.