Raymond Hoser described the Australian population as a separate subspecies "Chondropython viridis shireenae", after his wife Shireen, noting that the taxon consistently had white markings along the backbone, whereas snakes from New Guinea and Indonesia only sometimes had this trait, and the molecular analysis would bear out the distinctness. A genetic study by Lesley Rawlings and Stephen Donnellan in 2003 of mitochondrial DNA of the green tree python found two distinct lineages: a southern lineage comprising populations of Australia, Aru Islands, and New Guinea south of the central highlands, and a northern lineage of New Guinea north of the central highlands and Vogelkop Peninsula, and Biak Island. The two likely diverged around 5 million years ago with the rising of the central mountain range in New Guinea. The authors suggested this might explain poor breeding success in Australia if people were unknowingly trying to breed the northern and southern green tree pythons, as they were not closely related. The two taxa are indistinguishable in appearance.