Phylogenetic analysis of the Squilloidea (Crustacea:Stomatopoda)

Abstract

Squilloidea is the most speciose of the stomatopod superfamilies and comprises more than 40 genera. Until 2001, three families were recognised: two extant (Harpiosquillidae, Squillidae) and one extinct (Ursquillidae). Recent studies, however, suggested that Harpiosquillidae is nested among other squillids and was thus synonymised with Squillidae. Interrelationships of all squilloid genera are studied by cladistic analysis based on somatic morphology. Results are used to assess the familial classification and investigate the ‘shape’ of squilloid evolution. The phylogeny of the squilloids shows general trends in the armature of the raptorial claw, increased dorsal carination, a tendency for bilobation of the lateral processes of the exposed thoracic somites, and a change in telson shape from trianguloid with movable submedian teeth, to quadriform with fixed submedian teeth. Harpiosquilla Holthuis, 1964 is deeply nested among other squillid genera, supporting the recent synonymy of the Squillidae and Harpiosquillidae. Characters of the late Cretaceous Ursquillidae show that it is highly derived and is therefore synonymised with Squillidae. Although the antiquity of Ursquilla Hof, 1998 does not show it to be a basal or stem-lineage squilloid, it does show that the squilloids had already undergone significant diversification by the end of the Cretaceous. Species of most squilloid genera are regionally restricted, either to the Indo-west Pacific or Atlanto-east Pacific. Only Alima Leach, 1818, Cloridopsis Manning 1968b, and Pontiosquilla Manning, 1995 are represented in both regions.