Before people and mammalian predators arrived in New Zealand, lizards were widespread and abundant. They still occupy virtually all habitats, from intertidal rocks to alpine bluffs, and from semi-arid Central Otago to rainforests in Westland. Lizards live on the Three Kings and Chatham islands, but not on the subtropical Kermadecs or the cold subantarctic islands.
In some parts of inland Otago up to eight lizard species occur together: a local form of the common gecko, the jewelled gecko (Naultinus gemmeus), and six species of skink.
Also in Otago, up to three large skink species may be found living near each other, but not in the same habitats. These are the grand skink (Oligosoma grande) on rocky outcrops, the green skink (O. chloronoton) in moist, well-vegetated areas, and either the Otago skink (O. otagense) on bluffs, or the scree skink (O. waimatense) on scree slopes. Up to three smaller skink species may also be present, each with its own particular habitat requirements.
Kawekaweau in Marseille
Māori call reptiles ngārara – a term that includes tuatara, lizards, and giant reptiles from tradition. One story tells of a giant forest lizard, the kawekaweau. In the Natural History Museum in Marseille, France, there is an unlabelled, stuffed lizard that could be this creature. It belongs to the genus Hoplodactylus, which occurs only in New Zealand. Where it was found and how it ended up in a French museum is unknown. In 1870 an Urewera chief killed a large lizard that resembled the Marseille specimen.
The geckos belong to the subfamily Diplodactylinae, a primitive group found only in Australia, New Caledonia and New Zealand. Other, modern geckos have colonised many remote Pacific islands, but Diplodactylids are less able to survive long ocean voyages aboard flotsam. Significant differences between New Zealand and Australian Diplodactylids suggest that geckos may have been in New Zealand for tens of millions of years, perhaps since it broke away from the Gondwana supercontinent, about 85 million years ago.
The diversity of skinks and genetic differences between species indicates that they must also have been in New Zealand for many millions of years. Just how they got there and where they came from is still debated. Some researchers suggest that skinks arrived from New Caledonia more than 40 million years ago, when the sea level was lower and it may have been possible to island-hop south. Others think that skinks and geckos came to New Zealand during the last 20 million years. Further research is likely to clarify this.
Many new lizard species have been recognised using DNA analysis, which has shown that what was once considered a single species is in fact several species. For example, the gecko previously classified as Hoplodactylus maculatus is now known to consist of nine species. Their geographically separated forms have evolved from a common ancestor. In another case, one previously recognised subspecies of skink, Oligosoma nigriplantare maccanni, was reclassified as four unique species, each with a specific habitat preference that stops them from interbreeding.