| Summary: | Different deep-sea sites are frequently characterized by a high number of species belonging to the same genus. In addition, some deep-sea genera (e.g. Acantholaimus, Monhystera, Halalaimus ) seem to be dominant and present worldwide. The genus Manganonema is present in all oceans in low to medium densities « 2%) and, apparently, restricted to the deep sea (600 m and deeper). The present study deals with a revision of the genus Manganonema based upon known species and nine new species, where only 5 were named due to the lack of males ( M. media sp. nov., M. pitilica sp. nov., M. robustus sp. nov., M. antarctica sp. nov., M. bussauensis sp. nov.). For the species identification, important characters are summarized in a pictorial key. The material studied was collected from six different sites: two in the North Atlantic (Europe), two in the Southern Ocean (Antarctic), one in the South-western Atlantic (Brazil), and one in Western Indian Ocean (Kenya). The species distribution suggests a high turnover of species between sites. Only one Manganonema species is recorded from two different sites in the Atlantic Ocean. These results suggest a high degree of endemism of species within the genus.
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