Two New Stick Insect Species Found in Australia, One With Eggs Never Seen in the Group
A University of Sydney team used DNA, museum specimens and more than 1,000 citizen-science photos to split two known species into five.
Some of Australia's most photographed insects have turned out to be more than they seemed. Researchers at the University of Sydney report that what scientists treated as two species of large stick insect in the genus Anchiale is actually five, including two species that are new to science.
The revision was published in the journal Austral Entomology and led by Dr. Braxton Jones, a postdoctoral research associate in the university's Molecular Ecology, Evolution and Phylogenomics Laboratory. The new species are Anchiale robusta and Anchiale mabiensis. Their ranges stretch from northern New South Wales up the Queensland coast and into the tropical north.
Anchiale robusta is a case of mistaken identity. It is common and was familiar to scientists, but it had been misidentified for decades. Anchiale mabiensis was found in the Mabi rainforest on the Atherton Tablelands in Queensland, a critically endangered type of rainforest.
The most striking feature of A. mabiensis is its eggs. Stick insect eggs have a cap, called an operculum, that the nymph pushes open to hatch. The operculum of A. mabiensis has inner rings that the team says have not been recorded before in stick insects or in the order Phasmida as a whole, including their closest relatives.
To tell the species apart, the researchers combined DNA analysis, museum collections, field surveys, captive breeding populations and more than 1,000 observations that members of the public had uploaded to the iNaturalist platform. "Taxonomy is often a bit like detective work," Jones said.
The work has practical value beyond cataloguing. Some of these large stick insects form plagues that strip leaves from trees, and the researchers say that knowing there are several species involved will help forestry and agriculture managers understand which one is causing damage and how it behaves.
The study was supported by the Australian Biological Resources Study and CSIRO. The authors say the finding shows how much of the continent's insect diversity remains undescribed, even in places that are well studied and close to cities.
The revision also shows why careful species counts matter for conservation. The Mabi rainforest where A. mabiensis lives is a critically endangered ecosystem, and a species that was unknown until now becomes one that managers can protect by name. A population that scientists once folded into a more widespread species could easily have been missed in any assessment of what the forest holds.
Australia is home to many of the world's largest stick insects, and several species are kept by hobbyists and photographed widely, which is how the citizen-science records piled up. Researchers say those casual photos, taken in backyards and parks, proved valuable evidence for where each species lives.
