New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (part 4).

Forty-eight species (including nine that are new) of the 288 Didemnidae now known from Australian waters are reported on in the present work. Dredged material is from benthic habitats in inter-reefal areas of the Great Barrier Reef and from deeper water canyons off northeastern and northwestern Tasmania. Collections from shallower waters of Port Davey (western Tasmania) and Kangaroo Island (South Australia) were hand-collected by scuba divers. Seven of the eight known genera of the Didemnidae are represented. Despite this emphasis on sampling in temperate waters, only 14 species (all indigenous) are recorded from around the southern half of the continent. The species diversity of this family is greater in the tropics, with 34 species being recorded. Nearly half of these are known also from the tropical western Pacific and some from the Indian Ocean as well. Tropical indigenous species are relatively few. [ABSTRACT FROM AUTHOR]