The taxonomic status, biogeographical distributions and existing collections are reviewed for all species of decapod crustaceans known from the vicinity of hydrothermal vents and cold (hydrocarbon or brine) seeps. To date, more than 125 species representing 33 families of decapods have been reported. Represented families are, in alphabetical order within infraorder, the penaeoid families Benthesicymidae and Sergestidae; the caridean families Alvinocarididae (all of which are vent or seep endemics), Crangonidae, Glyphocrangonidae, Hippolytidae, Nematocarcinidae, Oplophoridae, Palaemonidae, Pandalidae and Stylodactylidae; the anomuran families Chirostylidae, Galatheidae, Lithodidae and Parapaguridae; the brachyuran crab families Atelecyclidae, Bythograeidae (all of which are vent endemics), Cancridae, Epialtidae, Geryonidae, Goneplacidae, Homolidae, Majidae, Ocypodidae, Oregoniidae, Parthenopidae, Pisidae, Portunidae and Varunidae; the lobster (astacidean) family Nephropidae; and the thalassinidean families Axiidae, Callianassidae and Calocarididae. Some species appear to be vagrants, here defined as opportunistic species occasionally found in the vicinity of vent sites but not restricted to them. Other species, notably members of the shrimp family Alvinocarididae and the crab family Bythograeidae, are clearly endemics, known only from vent or seep sites and presumably restricted to them. All endemic vent shrimps, most of which were originally treated as members of the family Bresiliidae, are now treated as members of the family Alvinocarididae. The family Mirocarididae proposed earlier is no longer recognized following a recent review of the characters that define the genus Mirocaris and the family Alvinocarididae. Currently recognized vent-associated species of shrimp belong to six genera: Alvinocaris , Chorocaris , Mirocaris , Nautilocaris , Opaepele and Rimicaris ; the genus Iorania is no longer recognized. Several more genera and species are in various stages of description (manuscripts in press or in review). Of the endemic shrimp genera, only Alvinocaris has been reported from both hydrothermal vents and cold seeps. Vagrant shrimp species include members of the families Crangonidae (one species), Hippolytidae (several species in the genus Lebbeus ), Nematocarcinidae (genus Nematocarcinus , often seen but rarely collected), Oplophoridae (five genera), Palaemonidae (one species) and Pandalidae (one species of Chlorotocus questionably included).
