Ascidiacea (Tunicata) in Australian Waters of the Timor and Arafura Seas

Abstract

Fifty-seven species of Ascidiacea from Australian territories bounded by the Timor and Arafura Seas are discussed. The majority were known previously from western Pacific and/or Indian Ocean (including Australian) tropical waters, although 13 species are new. Discussions focus on geographic range and/or morphology of adults and larvae and their relationships. New records for a further 37 known species are listed. The majority (35) of species discussed, including 11 that are new (seven in the genus Didemnum, three in Polysyncraton and one in Trididemnum), are in the family Didemnidae. Trididemnum pseudodiplosoma (Kott, 1962), an indigenous species originally known from southern Australia, is recorded again from the Northern Territory. Diplosoma ferrugewn Kott, 200 I is proposed as a junior synonym of D. versicolor Monniot, 1994. Non-didemnid aplousobranch taxa, Polycitoridae, Holozoidae and Polyclinidae are represented, respectively, by Eudistoma spp. including the unusual E. ova tum Herdman, 1886 (which is redescribed); Distaplia spp. including a new, possibly tropical sister species of the temperate D. australiensis Brewin, 1953; and Polyclinum spp. including the tropical Polyclinum tsutsuii Tokioka, 1954 (also redescribed, together with its incubatory pouch). In other suborders, a multipapillate larva is described for Perophora modificata Kott; 1985 (Phlebobranchia); and tropical and sub-tropical species of the colonial styelid genus Symplegma (Stolidobranchia), including a new Australian species, are redefined and a key to their identification presented.