The phylogeny of the stomatopod Crustacea

Abstract

The stomatopods, or mantis shrimps, are malacostracan crustaceans of the subclass Hoplocarida. Extant hoplocarids belong to the order Stomatopoda and suborder Unipeltata, comprising the extinct, stem-lineage pseudosculdids and sculdids, and the crown group. Cladistic analysis including most or all genera of the unipeltatan families, and rooted to the extinct Tyrannophontidae, resulted in four most-parsimonious cladograms. The present results are more highly resolved and more robust than previous studies as the result of: more precise identification of suitable outgroups; a more complete outgroup data set, lessening the impact of missing data; and increased taxonomic sampling. The results largely support the existing five-superfamily classification, but as with two recent cladistic studies, Gonodactyloidea was polyphyletic. Gonodactyloidea is the basal crown-group superfamily and comprises mostly ‘smashers’. Two clades of ‘spearers’, Eurysquillidae and Parasquillidae, previously considered gonodactyloids, are more closely related to the Squilloidea and are referred to new superfamilies. The familial classification within Lysiosquilloidea is modified. Rather than deriving the ‘smashers’ from a long line of ‘spearers’, the present analysis suggests that the Unipeltata diverged in two broad directions from the outset. Hence, the gonodactyloid ‘smashers’ became specialised for hard substrates, and the remainder diversified into the other modern superfamilies, evolving more efficient ‘spearing’ claws, and occupying soft substrates.