Systematics or Phylogenetics

Stomatopods are a small but diverse group consisting of approximately 400 species, within 19 families and 100 or more genera (Debelius 2001). They are only distantly related to crabs and prawns as the stomatopod lineage split from other crustaceans around 200 million years ago (Debelius 2001).


Figure 1. A phylogeny of Malacostraca, with the focus on Stomatopoda (adapted from Ruppert, Fox & Barnes 2004).

Leptostraca is the sister taxon of Eumalacostraca, the latter comprises all the remaining malacostracan taxa (Ruppert, Fox & Barnes 2004). In the ancestral eumalacostracans, the exopods of the second antennae were developed into a scaphocerite, or antennal scale, that is lacking in Leptostraca (Ruppert, Fox & Barnes 2004). The phyllopodous thoracopods inherited from the early crustacean were converted into stenopods by adaptation of the endopods (Ruppert, Fox & Barnes 2004). The sixth pleopods became uropods, which in combining with the enlarged telson produced a tail fan (Ruppert, Fox & Barnes 2004). The caudal furca was lost (Ruppert, Fox & Barnes 2004).

Eumalacostraca is separated into Stomatopoda and Caridoida, the latter consisting of all remaining eumalacostraca (Ruppert, Fox & Barnes 2004). The stomatopods have triramous first antennae, raptorial anterior thoracopods, and respiratory pleopods (Ruppert, Fox & Barnes 2004). The caridoid rostrum is attached to the head and unmovable (Ruppert, Fox & Barnes 2004). A statocyst is present in each of the second antennae, although it is frequently secondarily lost (Ruppert, Fox & Barnes 2004).