Scientists from the University of Otago have described a new species of New Zealand gecko by utilizing a new method to analyze ancient DNA.
This unique species, once known as Duvaucel’s gecko, is now recognized in te reo Māori language as te mokomoko a Tohu. Its 600 or so mature individuals are restricted to the islands of Ngwhatu-kai-ponu (Brothers) and Kuru Pongi (Trios) in Cook Strait (Hoplodactylus tohu).
Researcher Lachie Scarsbrook, who directed the study at the University of Otago’s Department of Zoology, says that while these geckos and the Duvaucel’s gecko found on islands off the northeastern coast of North Island were once thought to be the same species, scientists have known for a long time that there are differences between these southern and northern lineages.
According to Mr. Scarsbrook, the geckos of the Brothers and Trios Islands are smaller, have distinct colors and patterns on their bodies, and exhibit unique genetic markers, all of which are essential to designate a new species.
The researchers didn’t know how different the mainland populations of the North and South Islands were until they utilized ancient DNA techniques to recreate their diversity, which had been lost to extinction. More over five million years, to be precise.
This article, published in the journal Zootaxa, explains te mokomoko a Tohu, which was made possible by a new way of collecting genomes from small bones without damaging them in the process.
The two tiny populations on the Brothers and Trios Islands, as well as those recently translocated to Mana Island, are currently the only known examples of Hoplodactylus tohu, Mr. Scarsbrook explains.
Because of this, the IUCN Red List has reclassified both the Duvaucel’s gecko and the te mokomoko a Tohu as critically endangered.
Although these islands have served as a refuge from certain rodents and other invasive predators for ages, the consequences of climate change and the incursion of predators pose serious threats to the continued existence of te mokomoko a Tohu.
Dr. Sharon Barcello-Gemmel, Rangatira of Te Ātiawa o Te Waka-a-Māui Trust, the iwi with mana whenua over the Ngāwhatu-kai-ponu Islands, generously suggested the species epithet tohu.
Her tupuna, Hone Kākahi, also known as Tohu Kākahi, was a pioneering pacifist whose efforts in the decades before the invasion of Parihaka are honored by her name.
Tohu was captured and then made his way to Dunedin on a sea voyage that took him from Whakatū (Nelson) via the Ngawhatu Islands and over the whole ancient and modern range of te mokomoko a Tohu.
Mr. Scarsbrook, who is finishing up his DPhil at Oxford, adds that working with the local iwi to describe this new species has been an extensive and highly fulfilling process.
The researchers intend to emphasize the value of iwi involvement and collaboration in science by giving this species a te reo Māori scientific and common name: te mokomoko a Tohu (Hoplodactylus tohu).
He also noted how the process brought to light the differences between te reo Māori and the standards for scientific naming set down in the International Code of Zoological Nomenclature (ICZN).
Taxonomy has the capacity to either prevent or expedite the extinction of a species because of the lasting impact of the scientific names given to them. The researchers want to see te mokomoko a Tohu included into the expanding discussion throughout the world about the need to loosen up taxonomic terminology.
The researchers go on to say that more research utilizing these innovative methods is desperately needed to support evidence-based conservation management, which in turn would lead to successful kaitiaki [guardian] practices, which would ensure the survival of te mokomoko a Tohu.
If scientists, conservationists, and Tangata Whenua don’t know what kinds of animals exist, they can’t hope to preserve them from extinction, as Mr. Scarsbrook puts it.
Ancient DNA study on Hoplodactylus geckos has barely scraped the surface of what researchers know about gecko, skink, frog, and tuatara diversity in Aotearoa at the time of human settlement and how it has altered since then.
Lachie Scarsbrook et al, Revision of the New Zealand gecko genus Hoplodactylus, with the description of a new species, Zootaxa (2023). DOI: 10.11646/zootaxa.5228.3.3