Summary
Two superficially similar species, Eusirus perdentatus Chevreux, 1912, and E. propeperdentatus Andres, 1979, have overlapping geographic distributions around Antarctica. Here, revisions are suggested for both species to clarify their status and distribution and to facilitate identifications (important characteristics used to separate the two species are listed). Although Eusirus propeperdentatus was not recognised as a species until 1979, illustrations of it (attributed to E. perdentatus) appeared in the literature as early as 1949. New illustrations and descriptions of specimens from the Prydz Bay region of East Antarctica are presented for both species. Trawl data indicate that E. perdentatus is benthic (usually caught in bottom trawls) whereas E. propeperdentatus is pelagic (usually caught in mid -water trawls). A depth cline involving morphological differences in pereopod structure is documented for E. perdentatus, suggesting very limited movement away from natal sites.