Phylogeny of Antarctic Epimeria (Epimeriidae: Amphipoda)

Abstract

Amphipoda belong to the most abundant benthic organisms of Antarctica, the Epimeriidae being one of the most dominant families. Morphological characters are used to explore relationships between the species of all Antarctic Epimeria, the genus representing 70% of Antarctic epimeriid species. Additional Epimeria from the deep sea off Brazil, the Tasman Sea and from shallow Norwegian waters are analysed. Species of Epimeriella and Metepimeria, as well as iphimedoid taxa are also considered.  High intraspecific variation was observed, which was not related to size, sex, or locality and may indicate recent speciation of some Antarctic epimeriids.  The small number of taxa studied from the deep sea and the northern hemisphere and difficulty in defining apomorphic and plesiomorphic states does not allow us to present final conclusions about the origin of Antarctic Epimeria living on the Antarctic shelf. Nonetheless, deep-sea species from the mid-Atlantic form a clade with deep-sea species from the western Pacific and two of the three studied North Atlantic species. This supports the Watling & Thurston (1989) hypothesis that Antarctica acts as an evolutionary incubator.