You are probably familiar with kangaroos. Wallabies, too, and most likely quokkas as well.
Less famous are their small, endangered cousins, the bettongs. These little marsupials love to dig and have a thing for mushrooms.
Because of their size and relative scarcity, it has always been hard to work out exactly how many different species of bettongs there are and where they all live.
Scientists have believed there are five living species of bettongs – but our new research, published today in Zootaxa, changes our understanding of the diversity of these creatures. And knowing that might help us understand why many efforts to protect them have failed, and how we can do better in future.
A single bettong weighs just a couple of kilos, but can move tonnes of earth each year in an effort to find food. This makes them “ecosystem engineers”, turning the soil over and improving ecosystem health as they forage.
There have long been five acknowledged living species of bettong: the boodie, the woylie, the northern bettong, the rufous rat-kangaroo, and the eastern bettong. There are also a few subspecies that are thought to have gone extinct due to feral cats and foxes.
But our new study changes things.
We measured the skulls and teeth of 193 bettongs from museums across Australia, as well as in the Natural History Museum of London and the Oxford University Museum of Natural History. We also looked at their arm and leg bones to determine how the shape and function of their limbs can be used to tell between species, something that had not been done in detail previously.
The aim of our investigation was to better understand the woylie. It has always been difficult to identify woylie bones in fossil beds, so our work would also help palaeontologists in the field.
Our analysis surprisingly showed that what we have been calling a woylie was actually three separate species.
It was previously believed there were two subspecies of woylie.
The first is what we generally call a woylie: Bettongia penicillata ogilbyi, a living species found in Western Australia. The second is extinct: Bettongia penicillata penicillata (the brush-tailed bettong), once found in South Australia and New South Wales.
However, our study indicates there are enough differences in the teeth and skull to recognise these as two separate species.
We also identified an extinct third species, Bettongia haoucharae or the “little bettong”. Its partially fossilised remains were located in the Great Victoria Desert and Nullarbor Plain, indicating that it was well adapted for the arid outback.
