The first report of Apistobranchus Levinsen, 1883 (Family Apistobranchidae) in Antarctica was presented by Hartman (1967). Two species were later described: Apistobranchus glacierae Hartman, 1978 and Apistobranchus gudrunae Hartmann-Schroder & Rosenfeldt, 1988, which differed from A. glacierae mainly by having compound setae. Subsequently, ecological studies in Antarctica have identified both of these species. On the status of Antarctic Apistobranchus, we concluded that there is up to now, only one valid species, A. glacierae. The character 'compound-setae' referred for A. gudrunae is in fact simple limbate ones eventually splintered as described for A. glacierae. Other characters, also previously considered as diagnostics for A. gudrunae, did not differ in both species as shown by the observation of several specimens of different sizes and type material of A. glacierae and A. gudrunae. All the reports on the densities of Antarctic apistobranchids, including ours, show th at they have higher values in finer sediments of 20 and 40 m depth. The need of additional work, including the rearing of specimens in the laboratory and plankton analysis, is emphasized.
