Hoplodactylus tohu, commonly known as the Tohu gecko (Māori: mokomoko a Tohu), is a species of lizard in the family Diplodactylidae. It is endemic to New Zealand, where it is found in the Marlborough Sounds and Cook Strait region.
Taxonomy
The species was formally described in 2023 by researchers led by Lachie Scarsbrook at the University of Otago, in a paper published in the journal Zootaxa (Scarsbrook, Walton, Rawlence & Hitchmough, 2023). Prior to this description, the Tohu gecko was considered to be the same species as the Duvaucel's gecko (Hoplodactylus duvaucelii). Genetic testing and morphological analysis revealed that the two groups represent distinct, geographically separated taxa.
Hoplodactylus tohu is one of two recognized species in the genus Hoplodactylus, the other being Hoplodactylus duvaucelii. The extinct Hoplodactylus delcourti (the largest known gecko in the world) is also placed within this genus.
The Tohu gecko can be distinguished from the Duvaucel's gecko by several features: it is generally smaller at maturity (snout-vent length approximately 95–120 mm, compared to 110–161 mm for H. duvaucelii), has a proportionally shorter and blunter snout, a more pronounced brillar fold (scales over the eyes), and more well-defined blotched markings.
Etymology
The specific name tohu and the common name "Tohu gecko" refer to Tohu Kākahi, a pacifist ancestor of the Te Ātiawa iwi (tribe). Tohu Kākahi was taken prisoner by British forces during the invasion of Parihaka in Taranaki and was moved across the historical range of the gecko that bears his name. The Brothers Islands (Māori: Ngāwhatu-kai-ponu), where the largest extant population occurs, fall under the regional tribal authority of Te Ātiawa.
Description
The Tohu gecko is New Zealand's second largest gecko and the largest gecko species in the South Island. It is large and robust in build, with dorsal colouration in various shades of grey or olive brown. It has a distinctive pale crescent-shaped marking on the nape of the neck and pale irregular crossbar-shaped splotches down the dorsum extending to the base of the tail. The underside is pale and usually a uniform grey. The species has yellow eyes, prominent brillar folds, and large oval ear openings. It occasionally vocalises, producing sounds described as squeaks, squeals, croaking, and coughing.
Distribution and habitat
Fossil records indicate that Hoplodactylus tohu was formerly widespread across much of the South Island of New Zealand, including areas as far south as Otago. However, the species is currently restricted to a small number of islands in the northwestern Marlborough Sounds and Cook Strait, including the Brothers Islands, Trio Islands, and Sentinel Rock. A population of approximately 40 geckos, originally thought to be H. duvaucelii, was translocated to Mana Island in 1998, where the population has successfully established and bred. Additional translocations have occurred to two further islands in the Marlborough Sounds.
The species is largely nocturnal but actively regulates its body temperature by sun basking. During the day, it hides in tree hollows, under logs, stones, or bark, in rock crevices, or in petrel burrows.
Ecology and biology
The Tohu gecko is largely insectivorous but also consumes plant material, nectar, and fruit, including the berries of taupata (Coprosma repens). It is viviparous, giving birth to live young, with a low annual reproductive output of a maximum of two offspring annually or biennially. Gestation has been reported to range from five months to over a year. Individuals reach sexual maturity at approximately seven years of age and have been reported to live over 50 years in the wild.
The species is tolerant of conspecifics and may form social aggregations, which typically contain only one male.
Conservation status
Hoplodactylus tohu is classified as "Threatened – Nationally Increasing" under the New Zealand Threat Classification System. The species is restricted to predator-free islands, and its population is estimated to comprise only a few hundred mature individuals. Conservation efforts have included translocations to additional islands to establish new populations.
