An international team of scientists has revised the classification of Australia's most famous spider, the Sydney funnel-web.
With a bite more deadly to humans than that of any other spider, the Sydney funnel-web has long been considered a single species but new research published in the journal BMC Ecology and Evolution suggests that funnel-web spiders in the Sydney region actually represent three distinct species.
The new research was by scientists from the Leibniz Institute for the Analysis of Biodiversity Change in Germany, the Australian Museum in Sydney, and Flinders University in Adelaide.
The research team used a combination of anatomical and molecular (DNA) comparisons to study different populations of Sydney funnel-web spiders, documenting distinctions indicating that three species should be recognised-the 'classic' Sydney funnel-web (Atrax robustus), found from the Central Coast and throughout the Sydney Basin, the Southern Sydney funnel-web (Atrax montanus), which is most common in the Blue Mountains south and west of Sydney, and the Newcastle funnel-web, playfully dubbed 'Big Boy' by spider lovers, the largest of the three, which occurs only in the vicinity of the city of Newcastle, north of Sydney.
"Our research uncovered hidden diversity among funnel-web spiders," says lead researcher, Dr Stephanie Loria, from the Leibniz Institute.
"The Newcastle funnel-web, Atrax christenseni – dubbed Big Boy- is a totally new species. The 'true' Sydney Funnel-web, Atrax robustus centres on the North Shore of Sydney and the Central Coast, and the Southern Sydney Funnel-web, Atrax montanus, is a resurrected species name from 1914," says Dr Loria.
"None of these insights would have been possible without the use of historical collections and international collaboration."
Dr Helen Smith, an arachnologist (spider biologist) at the Australian Museum, says that though the Sydney Funnel-web was previously known to be variable in some of its characteristics, this variability had been difficult to analyse.
"When our international team of researchers 'reopened the case' on the Sydney funnel-web, we looked at fine morphological details and gene sequences across the region and found the species split into three distinct groups."
"We can now say that Atrax robustus [the 'true', or original Sydney funnel-web] mainly occurs from the Central Coast, NSW, south to the Georges River, extending as far west as Baulkham Hills. The heartland for the Sydney funnel-web's distribution really is where we always thought, in the leafy northern suburbs of Sydney," Dr Smith said.
Arachnologists Dr Bruno Buzatto from Flinders University and Dr Danilo Harms from Leibniz began these comparisons after learning that unusually large funnel-web male spiders had been brought to Mr Kane Christensen, who was then based at the Australian Reptile Park in NSW, as part of its venom program. These large spiders all came from Newcastle, a city 150 km north of Sydney.
Investigating further, the research team collected new specimens of funnel-webs from throughout the Sydney region, focusing on their DNA. They also compared newly collected spiders with older specimens in the Australian Museum collections dating back to the early 1900s.
Dr Danilo Harms, co-lead author, said the revised taxonomy for funnel-web spiders may have practical implications for antivenom production and biochemical studies on spider venoms.
Chief Scientist and Director, Australian Museum Research Institute, Professor Kris Helgen said spiders are impressive animals with incredible adaptations, including keen senses, spun silk, and a highly effective venom injection system.
"Spiders are older than the dinosaurs. In more than 300 million years of existence, they've mastered nearly every environment on Earth and play a vital role across global ecosystems. And they are astonishingly diverse-there are about 52,500 known living spider species, and potentially many more to discover," says Professor Helgen.
