Two New Stick Insect Species Have Been Discovered in Australia—and Another One Was Hiding in Plain Sight
The new discoveries emphasize that scientists have a lot left to learn about insect diversity, even in areas with many observations
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Australian researchers have described two new species of stick insects, the long, crawly creatures that camouflage among thin branches or leafy twigs.
Their findings, published in Austral Entomology on September 21, add to the known diversity of the genus, Anchiale, that’s already wide-ranging and often strange.
“There’s quite a lot of them, and they can hatch in large proportions and population sizes,” study co-author Braxton Jones, a researcher at the University of Sydney in Australia, tells the Guardian’s Donna Lu. Despite their numbers, “there’s so much we don’t know about them.”
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Stick insects belong to the order Phasmatodea, named from the Greek word for ghost—a nod to how the cryptic animals can seem to eerily disappear amid vegetation. Australia has about 130 stick insect species, and some 3,000 species creep through forests worldwide. In Australia, the biggest can grow more than two feet long, and the heaviest might weigh nearly as much as a golf ball. If camouflage fails, they might try to thwart predators by emitting a foul-smelling or irritating liquid, playing dead, detaching (and later regenerating) a leg or delivering a powerful kick.
“In movies, they try to design all these crazy aliens,” Jones tells the Australian Broadcasting Corporation’s Holly Richardson. “But all you have to do is just look at the insect world, because they already exist.”
By closely studying the anatomy and DNA of stick insects in museum collections and from the wild, Jones and his team noticed subtle differences between them. For instance, they examined the color, length and shape of the wings, the animals’ habitats and even their eggs, which can alone identify a stick insect species.
Quick fact: Producing clones
Although stick insects can sexually reproduce, some females can also use parthenogenesis—a type of reproduction that results in female-only eggs that are clones of the mother.
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One of the new species, called Anchiale mabiensis, lays unusual eggs that seem to have a lid with concentric rings. They are unlike any eggs that have been recorded among stick insects and their close relatives, ensuring that this species is distinct from the rest.
The other newly described species, Anchiale robusta, is found in the coastal rainforests of Queensland and stands out for its relatively large size and mottled wings. For decades, A. robusta had been known to scientists and photographed by insect enthusiasts, but it was misidentified as belonging to another species, Anchiale briareus.
“Even among some of Australia’s most photographed and frequently reported insects, we’re still finding species that have escaped scientific recognition,” Jones says in a statement. “Taxonomy is often a bit like detective work.”
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The new research made another taxonomical adjustment: A previously named stick insect species had, in 1908, been bundled together with Anchiale briareus. But now, Jones and his team reinstated the species, called Anchiale albopunctata, as a distinct insect, suggesting it had been mistaken for the other species for more than a century.
Conservationists say the new discoveries draw attention to the need to protect the insects’ habitats. Anchiale mabiensis, for instance, dwells in the Mabi Forest, a type of rainforest in northern Queensland. But large swaths of that original habitat have been cleared for agriculture, as Terry Carmichael of the Wet Tropics Management Authority tells the Australian Broadcasting Corporation.
"Now we have a very rare stick insect living in that Mabi Forest,” adds Carmichael, who was not involved with the study. “It just makes it more and more special.”
Had this research not been conducted, scientists likely wouldn’t know about the forest’s rare inhabitant. In this way, the work also stands as a testament to the value in both taking a close look at museum specimens and learning as much as possible about animals, even those that seem already well-observed.
The findings, Jones says in the statement, demonstrate the importance of “documenting Australia’s extraordinary biodiversity before we lose species without us having even discovered them.”