New host records: from Macropus rufogriseus for Labiosimplex clelandi, M robustus for Ls. aridus, Thylogale stigmatica for Ls. thetidis, and M. parma for Ls. bancrofti are reported. On re-examination of all material, Labiosimplex quasibancrofti was found to be morphologically indistinguishable from Ls. australis and is therefore a synonym of Ls. australis. A new species of Labiomultiplex, described from a single female from M parma, is differentiated by the shape of the lateral lips and Lm. kimberleyensis is redescribed from additional material collected from the type-host, Onychogalea fraenata, from Queensland. Two new species of Labiosimplex are described from macropodid marsupials from central Australia. Labiosimplex centralis sp. nov. from the stomach of Petrogale lateralis differs from the most similar of its congenors, Ls. thomasae (both lacking a gubernaculum), in having shorter spicules, a shorter dorsal lobe of the bursa, and in the form of the dorsal ray. Labiosimplex territoriensis sp. nov. from the stomach of M. antilopinus differs from all its congenors in having large multi-lobed oesophago-intestinal diverticula. A new species, Labiostrongylus arnhemensis sp. nov. from the stomach of M. bernardus from the Northern Territory, differs from its congenors in a suite of characters including the position of the deirids, the shape of the oesophago-intestinal diverticula, the length of the dorsal lobe of the bursa, the morphology of the genital cone and gubernaculum and the length of the female tail. A revised host-parasite checklist, including Labiostrongylinea from the island of New Guinea together with those occurring in Potoroidae, is given.