High genetic diversity within Epimeria georgiana (Amphipoda) from the southern Scotia Arc

DNA barcoding revealed four well-supported
clades among amphipod specimens that keyed out to
Epimeria georgiana Schellenberg, 1931, three clades with
specimens from the southern Scotia Arc and one clade with
specimens from the Weddell Sea. Detailed morphological
investigations of sequenced specimens were conducted,
through light and scanning electron microscopy. High
magnification (500–2,000 fold) revealed features such as
comb-scales on the first antenna and trich bearing pits on
the fourth coxal plate to be similar for all specimens in the four clades. Consistent microstructure character differences in the Weddell Sea specimens combined with high genetic distances (COI divergence>20%) allowed the description of Epimeria angelikae, a species new to science. Specimens of E. georgiana in the other three COI clades from the Scotia Arc were morphologically indistinguishable. Representative specimens of clade A are also illustrated in detail.
Our results on the high genetic divergences in epimeriid
amphipods support the theory of the southern Scotia Arc
being a centre of Antarctic diversification.