Australia's tiniest mouse weighing a little more than a 10 cent coin is not just one species spanning four states.
The delicate mouse, a native Australian rodent weighing just six grams, was thought to be a single species spanning from the Pilbara in Western Australia, to the Northern Territory, through Queensland and down to NSW.
But scientists have found there are three species.
"We're really excited to be able to announce the first new pseudomys species in centuries," Australian National University researcher Emily Roycroft told AAP.
Researchers found a preliminary clue in genetic sequencing of historical museum collections and field sampling that there was something different about the delicate mouse.
The discovery of the species was made using high-resolution genomic sequencing across the mice samples, looking at cranial results from skull and sperm morphology.
There is now the western delicate mouse or Pilbara delicate mouse, eastern delicate mouse and northern delicate mouse.
It's almost impossible to the untrained eye as all the species look superficially similar to each other.
The best way to tell the species apart is where they are geographically found.
Australia's native rodents are threatened by extinction because of feral predators such as foxes and cats as well as land clearing.
"We didn't know that these two new delicate species existed, they haven't had any conservation focus," Dr Roycroft said.
So what is next for the delicate mouse?
The new species will be assessed by federal and state governments to determine whether they need conservation listing and if priority funding and research attention is needed.
"There will definitely need to be a lot more research to work out whether there have been significant population declines in the new species,'' Dr Roycroft said.
"They probably haven't been monitored much because it was thought to be a very common widespread thing until now."
