Australian entomologists have described a spectacular new species of the stick insect genus Acrophylla from two female specimens as well as eggs.
Holotype of Acrophylla alta in nature. Image credit: Ross M. Coupland.
First described in 1835, Acrophylla is a genus of stick insects in the tribe Phasmatini.
Members of the genus are found in China, Australia, New Guinea and surrounding islands such as Tasmania and Larat.
The newly-described Acrophylla species occurs in the upland areas of the Wet Tropics Bioregion, Queensland, Australia.
“These locations include Mt Lewis National Park, Evelyn Tablelands (likely including the Maalan National Park), Topaz, Upper Barron, Mt Hypipamee and Danbulla,” said James Cook University’s Professor Angus Emmott and his colleague Ross Coupland.
Named Acrophylla alta, the new species measures up to 40 cm (16 inches) in length and weighs in around 44 g.
It has a generally light brown coloration, and is extremely well camouflaged despite its large size.
“There are longer stick insects out there in the region, but they’re fairly light bodied,” Professor Emmott said.
“From what we know to date, this is Australia’s heaviest insect.”
Acrophylla alta’s eggs were also important for identifying it as a new species.
“Every species of stick insect has their own distinct egg style,” Professor Emmott said.
“They’ve all got different surfaces and different textures and pitting, and they can be different shapes.”
“Even the caps on them are all very unique.”
The researchers suspect that one possible reason why Acrophylla alta was not discovered until now is that its habitat is simply too difficult to access.
“Their habitat could also be the reason behind their large body size,” Professor Emmott said.
“It’s a cool, wet environment where they live.”
“Their body mass likely helps them survive the colder conditions, and that’s why they’ve developed into this large insect over millions of years.”
“The discovery of such a large, new species of insect is testament to the importance of protecting remaining, biologically diverse habitats and ecosystems, as there may be further species of stick insects and other insects awaiting discovery and description therein.”
The discovery of Acrophylla alta is reported in a paper in the journal Zootaxa.
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Ross M. Coupland & Angus J. Emmott. 2025. A new giant species of Acrophylla Gray, 1835 (Phasmida: Phasmatidae: Phasmatini) from the highlands of the Wet Tropics, Queensland, Australia. Zootaxa 5647 (4): 371-383; doi: 10.11646/zootaxa.5647.4.4
