Stomatopod interrelationships: Preliminary Results Based on Analysis of three Molecular Loci

The mantis shrimps (Stomatopoda) are quintessential marine predators. The combination of powerful raptorial appendages and remarkably developed sensory systems place the stomatopods among the most efficient invertebrate predators. High level phylogenetic analyses have been so far based on morphology. Crown-group Unipeltata appear to have diverged in two broad directions from the outset - one towards highly efficient 'spearing' with multispinous dactyli on the raptorial claws (dominated by Lysiosquilloidea and Squilloidea), and the other towards 'smashing' (Gonodactyloidea). In a preliminary molecular study of stomatopod interrelationships, we assemble molecular data for mitochondrial 12S and 16S regions, combined with new sequences from the 16S and two regions of the nuclear 28S rDNA to compare with morphological hypotheses. Nineteen species representing 9 of 17 extant families and 3 of 7 superfamilies were analysed. The molecular data reflect the overall patterns derived from morphology, especially in a monophyletic Squilloidea, a monophyletic Lysiosquilloidea and a monophyletic clade of gonodactyloid smashers. Molecular analyses, however, suggest the novel possibility that Hemisquillidae and possibly Pseudosquillidae, rather than being basal or near basal in Gonodactyloidea, may be basal overall to the extant stomatopods. In this context, it is significant that in many respects, hemisquillids resemble the stem-lineage condition more so than any other extant forms.