As is true of the other fragments of supercontinent Gondwanaland—Madagascar, Australia and New Caledonia—New Zealand has remarkable levels of endemism among plants, birds and reptiles.
Plant endemism is very high in New Zealand. Nearly 1,900 of about 3,400 species of vascular plants are endemic. Endemism also extends to the genus level; 35 plant genera are found nowhere else in the world. An example is the endemic monotypic genus Desmoschoenus spiralis or Pingao golden sand sedge, a coastal plant used by the Maori people in traditional building construction.
The fern Loxsoma cunninghamii is one of the hotspot's "living fossils." Together with three species from Central America, L. cunninghamii constitutes the family Loxsomataceae, whose closest relatives existed 60 million years ago. The hotspot also has one endemic family, the Ixerbaceae, which is represented by a single species (Ixerba brexiodes).
Nearly 200 bird species regularly occur in New Zealand, nearly 44 percent are endemic. Unfortunately, the hotspot's existing bird diversity represents only a fraction of the species that once occupied the island. New Zealand has suffered 20 bird extinctions since 1500, including Stephens Island wren (Traversia lyalli), the only case in which an entire species was rendered extinct by the predatory instincts of a single introduced cat. Other historically extinct species include the giant flightless moas, which could grow to more than 3.5 meters in height, the bizarre flightless adzebill (Aptornis), which weighed up to 10 kilograms and bears no resemblance to any other known bird, and the largest eagle in the world, Haast's eagle (Harpagornis moorei), which preyed on moa.
A number of other species are highly threatened today, including the Critically Endangered kakapo (Strigops habroptilus), a large, nocturnal, terrestrial owl. Three of the four beloved kiwi species are also threatened: the Vulnerable tokoeka (Apteryx australis), Vulnerable great spotted kiwi (Apteryx haastii) and Endangered brown kiwi (Apteryx mantelli).
New Zealand also has the most diverse seabird community in the world, with around 80 species known to breed here. At least three-quarters of the world's penguin species breed in the New Zealand region, including the Endangered, endemic yellow-eyed penguin (Megadyptes antipodes).
Both land mammal species native to the hotspot are endemic bats, one of which is the only living representative of the endemic bat family Mystacinidae: the Vunlerable New Zealand lesser short-tailed bat (Mystacina tuberculata). This bat species is an oddity in that it walks about on all fours on the ground in predator-free environments. Its relative, the greater short-tailed bat (Mystacina robusta) is Critically Endangered and possibly extinct.
Nearly 40 species of reptiles are found in New Zealand, and all are unique to the islands. The fauna comprises geckos and skinks only, and there are no native snake species. In addition, a remarkable five of six reptile genera are endemic to the hotspot. The region also boasts an entire endemic order, the tuataras (Order Rhynchocephalia). The tuataras resemble iguanas and are primitive species that have existed since the dinosaur age, famous for their well-developed third eye. Although tuataras once ranged throughout much of the hotspot, the arrival of the Polynesia rat (Rattus exulans) greatly reduced their numbers.
Amphibians are represented in New Zealand by four primitive frog species of the endemic family Leiopelmatidae. All four species are threatened, among them the Critically Endangered Archey's frog (Leiopelma archeyi), which occurs on the North Island in the Whareorino range in the west and Coromandel ranges in the east, and has been severely affected by chytrid fungus.
Of the nearly 40 freshwater fish species native to New Zealand, about 25 (64 percent) are found nowhere else. The fish fauna is dominated by members of the family Galaxiidae, a group of coolwater trout-like fishes restricted to the southern tips of South America, Africa, Australia and New Zealand. Nearly 20 of the more than 50 galaxiid species known worldwide are found in New Zealand, and all but a few are endemic to the hotspot.
A distinctive element of the New Zealand biota is the widespread occurrence of gigantism. Although some of the giant forms include the now extinct flightless moas and Haast's eagle, this element is still noticeable in some giant insects, myriapods, flatworms, land snails, centipedes, slugs and earthworms. The world's heaviest insect, the weta or wingless cricket of Little Barrier Island (also known as Hauturu) weighs up to 70 grams and is one of 12 species of Deinacrida, the ancestors of which roamed the Jurassic forests.