A new species of long-necked turtle from the Chelodina longicollis group is described from northern Australia; the species Chelodina novaeguineae is restricted to southern New Guinea. The new species differs from its New Guinea counterpart in being a larger species with a broader shell and wider plastron, the skull having paired premaxillae and a narrower parietal ridge, having a single frontal bone, posteriorly partially dividing the parietals, in the form and relationship to the pterygoids of the vomer, and a narrower crista paroccipitalis.