Diversity of peracarid crustaceans (Malacostraca) from the abyssal plain of the Angola Basin

During the expedition DIVersity of the abyssal Atlantic benthos (DIVA-1) with RV “Meteor” in July 2000, samples were taken at seven stations by means of an epibenthic sledge north of the Walvis Ridge in the Angola Basin off Namibia in 5125-5415 m depth. Two hundred and forty one species of Peracarida are identified from the material so far. Dominant elements of the peracarid fauna were Isopoda, which were most abundant and diverse, 100 species were identified from 1326 individuals, followed by Tanaidacea with 50 species and 194 individuals, and Cumacea with 45 species and 479 individuals. Amphipoda were less frequent with 39 species and 150 individuals, Mysidacea were rarest yielding only 7 species and 34 individuals. The fauna is characterized by 118 rare species, most of them occurring only with single specimens at one station. Only 123 species occur at more than one station and only two species of the Eurycopinae (Isopoda) at all stations. The few species which are already known are either cosmopolitan or typical for the Atlantic Ocean, while elements known from the Southern Ocean are rare indicating that the Walvis Ridge is an effective distribution barrier for deep-sea organisms.