Two new species of native mice discovered in 'plain sight'

The three species of delicate mouse look similar to each other, and even resemble the invasive house mouse.

Two new native mammals have been discovered after researchers realised what was thought to be one species was actually three. Because all three types of delicate mice appear identical to the naked eye, it was only by using advanced genetic technology that the Australian National University was able to tell the difference.

“They've been hiding in plain sight for a while, but with these new methods we can uncover how they're actually unique,” lead researcher Dr Emily Roycroft told Yahoo News.

Delicate mice were clearly difficult for even experts to tell apart, but many Aussies would no doubt struggle to notice any differences between them and the invasive rodents that have spread across Australia since European settlement. Unlike introduced mice and rats, these native critters are actually beneficial to the environment, so it's important they are protected and not harmed. But can you spot the difference?

A house mouse (left) and a delicate mouse (right).
Can you tell which of these is a house mouse, and which is a delicate mouse? Answer at the end of this article. Source: Getty/Justin Wright

“We've got a whole bunch of different native rodents that most people don't even know about, and the delicate mice are among those” Roycroft said. “They play really important roles in our ecosystems in Australia. They act as what we call ecosystem engineers by distributing seeds and fungal spores throughout the soil.”

What are the names of the new delicate mice?

The established scientific name Pseudomys delicatulus now refers to the “northern delicate mouse”, and new names have been given to the other two species.

Those living across the Pilbara, Great Sandy Desert and southern Kimberley regions have been called the “western delicate mouse” (Pseudomys pilbarensis) or Kalunyja. And the species living in eastern Queensland and northern NSW has been called “eastern delicate mouse” (Pseudomys mimulus) or Kalla.

How much is known about these new mice species?

Advancements in technology such as genetic mapping and high-resolution CT scanning have led to dozens of new reptile, spider and insect discoveries. While new mammal finds are generally still rare, discoveries are on the increase — in August scientists were elated to describe two new species of carnivorous planigales in the outback.

The three species of delicate mice live across a massive stretch of country, from Western Australia’s rugged Pilbara, across the Northern Territory and Queensland, then down to the New South Wales border, but researchers are unsure how dense these populations are and whether they are under threat.

“We do still know a surprising little amount about many of our native mammals, and it's especially true for the smallest species,” Roycrot said. “The main differences between the Declicate Mice are genetics. They probably can’t interbreed. The other main difference is they've got very differentiated sperm morphologies.”

The new discoveries have been published in the journal Molecular Ecology. 

Delicate mice can vary in colour. Source: Ian Bool
Delicate mice can vary in colour. Source: Ian Bool

Can you tell the difference between a delicate mouse and house mouse?

As the name suggests, the delicate mouse is typically smaller than the house mouse, and only weigh between 6 and 15 grams. They sometimes have white on their stomachs and range in colour from yellow and grey to brown. Unlike their European cousins, their presence in the home is unlikely to lead to contamination, and they seldom bite.

In the picture above, it's the house mouse on the left, and the delicate mouse on the right. Did you pick the right answer?

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