Synopiidae Dana, 1853 (Crustacea, Amphipoda) of the Clarion-Clipperton Zone

The Synopiidae Austrosyrrhoe hamptonae sp. nov . and Syrrhoe manowitzae sp. nov . are morphologically described from the Clarion-Clipperton Zone, Pacific Ocean. Their descriptions are supplemented by molecular barcodes. Both Austrosyrrhoe and Syrrhoe have been recorded from only a few specimens in previous studies. The ten specimens reported here add to the sparse understanding of the Synopiidae. Also remarkable is the depth range of both genera, occurring in shallow waters of ~50 m to depths of ~5000 m. Prior to this study, the known depth range was less than 3000 m for Austrosyrrhoe and 3500 m for Syrrhoe . In the Clarion-Clipperton Zone the new species Austrosyrrhoe hamptonae sp. nov . was collected at 5109 m and Syrrhoe manowitzae sp. nov . from 4368 m, providing a significant increase in the maximum recorded depths for these genera.