Traditionally, two subspecies have been recognised: subspecies "albogularis" from northwestern Australia, the Northern Territory and Cape York, and subspecies "inopinatus" from central and southeastern Queensland. However, genetic work published in 2010 surprisingly found that the Carpentarian Barrier (south of the Gulf of Carpentaria) fostered a split between lineages east and west of it in the Pliocene, between 2.4 and 5.2 million years ago, and that a more recent split took place between 1 and 2.8 million years ago in northeastern Queensland. It is this more recent split that corresponds with the ranges of the two subspecies.