Observations on non‐didemnid ascidians from Australian waters (1)

Abstract

Thirty‐five species (including eight that are new) of non‐didemnid aplousobranch species and 25 phlebobranch (including one new) and stolidobranch species are discussed and a further 42 species in non‐didemnid taxa in all suborders are newly recorded. Material was taken by scuba diving in the waters around Kangaroo I. and other southern Australian and Tasmanian locations; and further material was taken by dredge from canyons off the southeastern Continental Slope and from inter‐reefal areas in the northern Great Barrier Reef region. The known geographic ranges of many southern Australian species are extended into Tasmanian waters and a new species of Rhopalaea is described from the Tasmanian Canyons. The genera Sigillina and Pseudodistoma are found to be diverse in Australian temperate waters, and they have many characters in common, suggesting a probable phylogenetic relationship that formerly was not recognised. The greatest diversity of species reported is from the vicinity of the northern Great Barrier Reef. Almost without exception these are non‐indigenous tropical species often extending into Australian temperate locations where they are sympatric with indigenous species found mainly around the southern half of the continent. Pyura stolonifera has a similar range in temperate Australian waters but appears also to occur on the South African and Chilean coasts in similar habitats and may represent a Gondwana relict.