During the French expedition BARESNAUT to the deep Caribbean Sea (Barbados Accretionary Prism), tanaidaceans were collected by scientists in the submersible Nautile at a depth of nearly 5 000 metres. These small benthic peracarids belonged to a new species of Pseudotanais G. O. Sars, which is described. Pseudotanais baresnauti, n. sp. resembles Pseudotonais lilljeborgi and P. macrocheles G.O. Sars, from northem Atlantic waters, but is distinguished primarily by the shape and setation of the antennae, uropods and pereopods. It is suggested that other small crustacean groups are relatively overlooked in deep-sea studies of hydrothermal vents and similarly active cold seep areas, where large chemosynthetic vestimentiferan worms or vesicomyid bivalves are often the most highly visible organisms present. The ecology of deep-sea tanaidaceans is largely unknown but it is likely that most species are detritivores.
Caribbean, deep-sea, cold seeps, Tanaidacea, Pseudotanaidae, submersible.