Sampling from different localities in the western Indian Ocean (Mozambique, Madagascar, Mauritius, and the Maldives) updates the ascidian list with new species and other poorly known species, or previously recorded only from the Pacific Ocean. Of the 27 species described, 16 are new, nine belong to the Polyclinidae, one to the Pseudodistomidae, and six to the Polycitoridae.
Ascidiacea, Polyclinidae, Pseudodistomidae, Polycitoridae, west Indian Ocean, new species.