Two new stick insect species turn up in Australia, and one hid in plain sight for decades

Researchers have formally described two new Australian stick insect species, Anchiale mabiensis and Anchiale robusta, in a paper published September 21 in the journal Austral Entomology. One of them turns out to have been hiding in plain sight: insect enthusiasts had been photographing Anchiale robusta for decades, but every one of those sightings was filed under the name of a different, already-known species.

The work, led by postdoctoral researcher Braxton Jones at the University of Sydney’s MEEP Lab and Aola Richards Sydney Insect Hub, also untangled a mixup that had gone unnoticed since 1908. It relied on DNA analysis, museum specimens, field surveys and citizen-science photographs to sort out which insects belonged to which species after more than a century of confusion. Funding came in part from the Australian Biological Resources Study and a CSIRO postgraduate scholarship, support aimed specifically at closing exactly the kind of taxonomic gap this project ended up finding three separate times over.

Anchiale mabiensis: an egg lid never recorded in any stick insect

Anchiale mabiensis lives exclusively in Queensland’s Mabi Forest on the Atherton Tablelands, a rainforest type so reduced that it now falls under a federal recovery plan as a listed threatened ecological community. The species is comparatively small and slender for its genus, with females reaching roughly 11.5 centimeters, and feeds on gray sassafras. What set it apart during description, according to the Austral Entomology paper, was its egg: a brown, less glossy shell topped with a distinct lid bearing two to three concentric rings, a structure never previously documented in stick insects or any of their closest orthopteroid relatives.

Terry Carmichael of the Wet Tropics Management Authority connected that rarity directly to the forest it came from. “It just makes it more and more special,” Carmichael said of finding an undescribed species confined to one of the region’s smallest and most fragmented rainforest remnants.

Anchiale robusta: photographed for decades under someone else’s name

Anchiale robusta is the larger of the two new species, with females reaching up to 16.2 centimeters, and ranges across at least 450 kilometers of Queensland’s coastal rainforest between Tully and areas north of Cooktown. It feeds on a broader range of plants than its Mabi Forest relative, often acacias, and defends itself by flashing dark, patterned hindwings when disturbed.

None of that made it easy to spot as a separate species. Anchiale robusta had been known to scientists and photographed by insect enthusiasts for decades, misidentified the entire time as Anchiale briareus. Sorting it out required going back through museum collections, wild surveys and years of amateur photographs and captive-breeding records to establish that the two insects were never the same species at all, just similar enough to fool a century of casual identification.

A 1908 filing error corrected for Anchiale albopunctata

The same research separated out a third species, Anchiale albopunctata, which had been lumped together with Anchiale briareus in the taxonomic record since 1908. That reclassification, based on anatomical and genetic evidence, restores a species that had effectively been invisible in the scientific literature for well over a hundred years, filed under a name that was not its own for longer than either new species has existed as a described entity. Anchiale albopunctata occupies central Queensland, geographically distinct from both the Mabi Forest range of A. mabiensis and the Tully-to-Cooktown coastal strip where A. robusta lives, which may be part of why the three insects were never disentangled sooner: none of them were competing for attention in the same patch of rainforest.

Stick insects as a group already number more than 3,500 described species worldwide, according to background compiled on the order Phasmatodea, with researchers widely expecting many more to remain unnamed. Their signature defense, mimicking sticks and leaves so closely that some species sway to imitate wind-blown vegetation, is also what makes them so easy for taxonomists to overlook or confuse for decades at a stretch.

A plague species that may turn out to be several species

Jones’s team at the University of Sydney flagged a further complication still unresolved: a stick insect known for periodically reaching plague numbers in parts of Australia may itself be a bundle of multiple species rather than one, a finding the researchers say could matter for how forestry and agricultural operations manage outbreaks. A likely undescribed species from Cape York surfaced during the same survey work, though the team says it needs more specimens before it can be formally named. Untangling that plague-forming group would mean applying the same combination of DNA sequencing, museum comparison and citizen-science photography that separated mabiensis, robusta and albopunctata from each other in the first place.

Two new names went into the record this month, one old name came back after 118 years, and at least two more identification questions remain open in the same patch of Queensland rainforest where all of it was found.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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