Biogeographical distribution of the benthic thecate hydroids collected during the Spanish "Antartida 8611" expedition and comparison between Antarctic and Magellan benthic hydroid faunas

The biogeographical distribution of the benthic hydroid species collected d uring the Spanish Antarctic expedition "Antartida 8611" has been studied. A n inventory of the Antarctic and Magellan benthic thecate hydroid faunas, a long with a comparison between the two, have been also carried out. 104 and 126 species of thecate hydroids have been considered in the Antarctic and Magellan areas, respectively. 72 species (69%) of the Antarctic species and 49 (39%) of the Magellan species are endemic. 23 species are present both in the Antarctic Region and in the Magellan area, representing 22% and 18% respectively, and indicating an important relationship between both faunas.