For such an arid region, the Pilbara supports a great diversity of long-legged flies.

I recently completed a study of the long-legged fly family Dolichopodidae (Diptera) from the Pilbara region, Western Australia. This was an expansion, of the environmental impact work I did for Chevron Australia identifying the insects collected on Barrow Island, which lies off the Pilbara coast and is a major storage site for exporting natural gas.

Diaphorus karijini
Diaphorus karijini Image: Dan Bickel
© Australian Museum

For such an arid region, the Pilbara has a very rich fauna with 41 species. During my research I came to realise that 19 of these were unknown to science, and so have just described and named them. Many of the species are associated with rivers that have permanent waterholes. One such area, the Fortescue River had a grand total of 30 species of long-legged flies!

One site in particular, Millstream, is an important biodiversity “hotspot,” and is the only known location of a dolichopodid genus that has only a single species: Pilbara octava. This species is quite strange and has no close relatives. I think it is an old relict group from the time Australia was covered by forest some 60 million years ago. It is now isolated at Millstream as a refuge from the progressive drying of the Australian continent for the last 30 million years. All related groups appear to be extinct, and it alone persists only at this permanent waterhole on the Fortescue River.

This research highlights the rich biodiversity that exists in the Australian arid zone. The reality is that most small-sized invertebrates (less than 3 mm in length) are known mostly by family level groupings, with only a handful of species described. One can find undescribed species even in Australia’s large metropolitan areas – it’s just that there are far more species than there are interested workers. Biodiversity is all around us, and offers endless opportunities for investigation, even by interested amateurs.

Dr Dan Bickel
Principal Research Scientist

More information:
Bickel, D. J. 2013. The family Dolichopodidae (Diptera) of the Pilbara region, Western Australia in its Australasian biogeographic context, with the description of 19 new species. Records of the Western Australian Museum, Supplement 83: 291–348.