New material of Gumardee pascuali Flannery et al., 1983 (Marsupialia: Macropodiformes) and two new species from the Riversleigh World Heritage Area, Queensland, Australia

New specimens of the late Oligocene macropodiform, Gumardee pascuali, are described, as well as two new late Oligocene to early Miocene species, G. springae sp. nov. and G. richi sp. nov. Species of Gumardee exhibit a unique combination of features, including very long upper and lower third premolars, partially lophodont molars and, in dorsoventral plane, concave lower molar row and convex upper molar row. We combined two morphological matrices to assess the phylogenetic relationships of these species. Our analysis recovered species of Gumardee as a well-supported monophyletic group, nested within Potoroinae. Gumardee richi and G. pascuali appear to be more derived than G. springae in having a more strongly developed posthypocristid that is almost hypolophid-like.