Hexactinellida (Porifera) from the ANDEEP III Expedition to the Weddell Sea, Antarctica

New Hexactinellida from the deep Weddell Sea collected in 2005 during the ANT XXII/3 expedition (ANDEEP III ) are described. This hexactinellid fauna includes 12 species from 8 genera, 2 of which are new to science: Lophocalyx profundum n. sp. and L. topsenti n. sp. It further contains the first record of Caulophacus (Caulodiscus) valdiviae in the Weddell Sea, and the second findings of the species Acoelocalyx brucei and Caulophacus (Oxydiscus) weddelli since their original descriptions. The Southern Ocean deep-sea, including the deep Weddell Sea, still offers a challenging potential for the discovery of new taxa.