The genusLycianthes(Dunal) Hassl. (Solanaceae) has in the past been treated as a section of the large genusSolanumL., but is more closely related toCapsicumL. The eighteen species ofLycianthesoccurring in Australia, New Guinea (defined as the island of New Guinea, comprising Papua New Guinea [incl. Bougainville] and the Indonesian provinces of Papua Barat and Papua, plus the surrounding islands connected during the last glacial maximum) and the Pacific Islands are here treated in full, with complete descriptions, including synonymy, typifications and synonyms, distribution maps and illustrations. The history of taxonomic treatment of the genus in the region is also discussed. These taxa occupy a diverse range of forested habitats, and are in diverse in habit, from small shrubs to large canopy lianas to epiphytic shrubs. They are for the most part rarely collected, and many are endemic (14 of the 18 species treated here). Australia has a single endemicLycianthesspecies (L. shanesii(F.Muell.) A.R.Bean). Nine species are found in both Indonesia and Papua New Guinea, one in Indonesia only, four in Papua New Guinea only, andL. vitiensis(Seem). A.R.Bean is known from Bougainville (Papua New Guinea) and the south Pacific as far east as Samoa.Lycianthes lucensS.Knappsp. nov.is described from the islands of Lihir, New Ireland and the Louisiade Archipelago of Papua New Guinea. The cultivatedL. rantonnetii(Carrière) Bitter is also treated in full, in this region known currently only from Australia; it is native to southern South America. Preliminary conservation assessments are presented for all species except the cultivatedL. rantonnetii.
