The male of the deep-living hyperiid Hyperoche shihi Gasca, 2005 (Peracarida: Amphipoda) and a new symbiotic association in the Gulf of California

Abstract

From samples of deep-water zooplankton, obtained in the Gulf of California, female and male specimens of the rare deep-living amphipod Hyperoche shihi Gasca, 2005 were collected. The adult male is slightly larger than the female and it has the distinctly large chela of pereopod II. A full description of the male is provided to complement the morphological information of this unique hyperiid species. This is the only deep-living species of Hyperoche Bovallius, 1887 known. These specimens were found in a symbiotic association with the coronate scyphomedusa Nausithoe rubra Vanhöffen, a deep-living form. The female was previously reported from the bathypelagic hydromedusa Chromatonema erythrogonon (Bigelow); hence, the host range of H. shihi is expanded and includes a scyphomedusa. There are no previous records of hyperiids associated to species of Nausithoe Kölliker. The amphipods were found grasped to the medusan exumbrella and were moving to the inner part of the medusa.