Australian little native mouse actually 3 species in a trench coat

Australia can add two new species to its native rodent roster.

Researchers identified that Pseudomys delicatulus, often called delicate or little native mouse (or among the Kunwinjku people of western Arnhem Land – Kijbuk.) which was previously thought to be a single species, is in fact 3 distinct ones.

Australian delicate mice are the continent’s smallest rodents weighing in at as little as 6 grams with a head and body length of only 55-75mm.

“Thanks to new genetic technology, we’ve confirmed the delicate mouse is 3 species, not 1,” says Dr Emily Roycroft, an evolutionary biologist from the Australian National University and lead author of a new study in Molecular Ecology. “Identifying undescribed species and giving them official names goes a long way to making sure they’re properly looked after.”

Before now it was thought that a single species of Pseudomys delicatulus spanned much of northern Australia from the Kimberley in Western Australia, the Top End in the Northern Territory and the wet tropics of Queensland.

Delicate mouse 2. Credit isaac clarey cc by nc 850
Delicate mouse, Litchfield National Park, Northern Territory. Credit: Isaac Clarey (CC BY-NC)

This discovery means that important conservation work can be better directed towards all 3 species.

“The two new species haven’t had any conservation or research attention, because we didn’t know they were there,” says Roycroft.

“We don’t know, for example, if population declines have gone undetected as a result of all three species being assessed as a single unit.

“The delicate mouse has not been a conservation priority – but that’s because it was thought to have a distribution three times larger than it actually does. This will allow us to reassess.”

The species belongs to the genus Pseudomys, whichcontains other native rodent species such as the New Holland mouse (Pseudomys novaehollandiae), smoky mouse (Pseudomys fumeus), and Gould’s mouse (Pseudomys gouldii).

“House mice [Mus musculus], black rats [Rattus rattus] and brown rats [Rattus norvegicus] are invasive species brought to Australia since European colonisation. They’re very different to native rodents, both evolutionary and ecologically. They compete with our native species for resources,” says Roycroft.

“Delicate mice are part of a group of native rodents that have been evolving in Australia for the last five million years. They’re a crucial part of Australia’s natural environment and ecosystems.

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