The present collection was made on the south and west coasts of Madagascar between 90 en 465 meters depth and includes 17 species of calyptoblastic hydroids, belonging to six families: Campanulinidae, Lafoeidae, Campanulariidae, Syntheciidae, Sertulariidae and Plumulariidae. Twelve are recorded for the first time from Madagascar, while three of these are new for the Indian Ocean and one is described as new (Tulpa costata). Endemic species represent half of the collection and are numerically more important than cosmopolitan, tropical-indopacific, and southern species. A comparative study of bathymetrical characteristics of species from Madagascar and around the world allows to distinguish three groups of species: deepsea species, which have a very wide... |