The platypus Ornithorhynchus anatinus is an endemic monotreme species with a wide latitudinal distribution in eastern Australia, including Tasmania. Understanding of the phylogeography within this species is very limited at present and represents a gap in the documentation of Australia's unique biodiversity. We analysed mitochondrial DNA sequences (partial control region and complete cytochrome b, including portions of flanking tRNAs) of 74 individuals from across the distribution of the species. Phylogenetic analysis of the concatenated sequences corroborated the primary split within the platypus, showing two major clades: one from mainland Australia and the other from Tasmania/King Island. Estimates of divergence times suggest that these clades last shared a common mitochondrial ancestor~0.7-0.94 Ma. Using an extended dataset of partial control region sequences from 284 individuals, we found evidence of genetic structure between river basins, primarily within mainland Australia, as well as an additional divergent lineage in North-eastern Australia. Overall, few haplotypes were shared between river basins. Analyses of molecular variance of the control region sequences indicated low rates of gene flow and significant divergence, particularly at the river basin and geographical area scales.

The saltwater crocodile is distributed throughout south-east Asia and Australia. In Australia, it is most abundant in the Northern Territory and Queensland, where it is sustainably farmed for its skins and meat. The aim of this study was to elucidate the relationships and genetic structure among saltwater crocodiles from the Northern Territory of Australia using mitochondrial control region sequences from 61 individuals, representing nine river basins and six of unknown origin, as well as published sequences from other regions. Eight mitochondrial control region haplotypes were identified among both published and novel sequences. Three of the haplotypes appear to be restricted to specimens from northern Australia, with a single haplotype being the most widely dispersed across all river basins. Although Analysis of Molecular Variance provides some support for differentiation among river basins, the frequency of shared haplotypes among these geographical units and median-joining network analysis do not support a clear genetic structure or phylogeographic pattern for saltwater crocodiles in the Northern Territory. The results of this study will assist in furthering our understanding of the genetic diversity of wild saltwater crocodile populations used for ranching in the Northern Territory, as well as providing a framework for assessing the origin of unknown specimens in the future.