Numerous studies have been carried out on marine taxa of the Gulf of Aqaba region, but few have concentrated on gelatinous zooplankton. Here, a new collection of pelagic hydrozoan siphonophore species is described from a study made during December 2013, whilst snorkelling along the Israeli coast of the Gulf of Aqaba to a depth of 5 m. Ten species were identified, including two species present in both post-larval and adult life stages. Four species are first records for the Gulf, and almost all the specimens collected were found to be associated with one or more hyperiid amphipod crustaceans or phyllosoma lobster larvae. Two of these crustacean species (Thamneus rostratus and Phronima colletti) are first records for the Red Sea region, a third (Parascelus edwardsi) was previously observed in this area, but not in the associations here recorded, and a fourth (Palinurellus wieneckii) is found to have undergone a northward extension of its distributional range. Moreover, our observation of P. wieneckii phyllosoma larvae attached to colonies of Agalma okenii constitutes the first evidence of palinurid (spiny lobster) association with siphonophores. The siphonophore taxa found in this study and those from previous studies are tabulated, and species richness discussed in relation to species lists published from other recent tropical studies worldwide. The hyperiid amphipod taxa identified are also tabulated and discussed in relation to the nature and possible means of invasion of gelatinous host siphonophores by crustaceans.
