Abstract
The genus Eurythenes S.I. Smith in Scudder, 1882 was previously considered as consisting of three highly distinctive species: E. gryllus (Lichtenstein in Mandt, 1822), E. thurstoni Stoddart & Lowry, 2004 and E. obesus (Chevreux, 1905). E. gryllus has been considered as a common cosmopolitan and eurybathic species recorded down to a depth of 7800 m. However, the analysis of DNA sequences (COI, 16S, 28S) of newly collected specimens combined with GenBank sequences revealed the existence of nine genetic lineages within E. gryllus sensu lato. Specimens were recovered by tree-construction methods in distinct, well-supported clades and were separated by genetic divergences in the same range as interspecific values documented for other lysianassoid species. Furthermore, in some cases, different lineages were found at the same sampling locality. Specimens of six of the nine clades were examined directly. With one exception, these clades are separated by small but consistent morphological differences. As a consequence, five morphospecies are recognized herein within the E. gryllus complex: E. andhakarae sp. nov. (West Antarctica, abyssal), E. gryllus (bipolar, bathyal), E. magellanicus H. Milne Edwards, 1848 (Cape Horn and Brazil Basin, abyssal), E. maldoror sp. nov. (nearly cosmopolitan, abyssal), E. sigmiferus sp. nov. (at least West Atlantic, possibly nearly cosmopolitan, abyssal).