Unidentified cestodes and 14 species of nematode and larvae that could not be placed to family level, were collected from the digestive tracts of 27 individuals of Paramelomys lorentzii, four of Mammelomys lanosus and a single M. rattoides from Papua New Guinea and Papua Indonesia. Of these three were new species. Hughjonestrongylus woolleyae sp. nov. can be distinguished from its congeners in having up to 26 ridges in the synlophe and a dissymmetric dorsal ray. Parvinema bafunminensis gen. nov., sp. nov. can be distinguished from all other genera in the family by the combination of features in the synlophe; with a carene, up to 17 ridges, and the pattern of ridge sizes. Parvinema helgeni sp. nov. differs from P. bafunminensis in the length of the spicule and the number of eggs in the uterus. The nematode assemblage of P. lorentzii had similar species richness to, and was also dominated by heligmonellids, as that of Paramelomys rubex, although the two assemblages differed in species composition.