A note on the genetic similarity between shallow- and deep-water Epistominella vitrea (Foraminifera) in the Antarctic

Many Antarctic species are known to have large bathymetric ranges. However, little is known about the genetic diversity of populations living at different depths. In certain microfauna- and meiofauna-sized taxa, some morphospecies can be divided into several cryptic genetic species. To test whether cryptic diversity is linked with depth of occurrence in Southern Ocean foraminifera, we compared ribosomal DNA sequences of selected calcareous foraminiferal species from shallow localities in McMurdo Sound and deep ones in the Weddell Sea. We found that at least one species, Epistominella vitrea, was genetically almost identical between the two localities, having a bathymetric range of over 1000 m. Our study provides molecular evidence for an extraordinarily large depth migration of Antarctic shelf foraminifera. It also suggests a relationship between populations of foraminifera from widely separated geographic regions of the Southern Ocean.