Biodiversity is being lost at an alarming rate, largely as a result of human activities. To combat this pattern of decline we need to define taxonomic units and identify undescribed species so that biodiversity can be effectively managed. Despite being well studied across much of their Australian range, the petaurid species found in northern Australia is surprisingly unknown. The species is currently classified as a sugar glider (Petaurus breviceps ariel), although molecular work revealed that it has closer affiliations to squirrel (P. norfolcensis) and mahogany (P. gracilis) gliders, both of which occur many hundreds of kilometres away on the eastern seaboard. Over the past 2 years we have trapped at locations across the top end, collecting tissue samples and morphological measurements from >40 animals. We have also measured ~298 petaurid skulls held in collections across Australia and redescribed the P. b. ariel type held at the British Natural History Museum. Phylogenetic and morphological analyses indicate that P. breviceps currently consists of at least two species (P. breviceps and P. sp nov). As well as establishing the identity of the savanna glider our research will investigate the existence of two additional distinct genetic lineages within the genus Petaurus and what this means for the current species and subspecies designations and distributions. Elucidating the taxonomic identity of this poorly researched glider will enhance our understanding of the unique biodiversity of northern Australia. This is of particular interest in the wake of small mammal declines that are currently being experienced in this region.