The crocodile monitor (Varanus salvadorii), also known as the Papuan monitor or Salvadori's monitor, is a species of monitor lizard endemic to New Guinea. It is the largest monitor lizard in New Guinea and is one of the longest lizards, verified at up to . Its tail is exceptionally long, with some specimens having been claimed to exceed the length of the Komodo dragon, however less massive.
Crocodile monitors are arboreal lizard with a dark green body marked with bands of yellowish spots. It has a characteristic blunt snout and a very long prehensile tail. It lives among the mangrove swamps and coastal rainforests of the southeastern part of New Guinea, feeding opportunistically on everything from birds and small mammals to eggs, other reptiles, amphibians and carrion. Its large, backwards-curving teeth are better adapted than those of most monitors for seizing fast-moving prey. Like all monitors, it has anatomical features that enable it to breathe more easily when running than other lizards, and is sometimes considered one of the most agile monitor species.
Crocodile monitors are threatened by deforestation and poaching, and are protected by CITES. Little is known of its reproduction and development, as it is difficult to breed in captivity. Attempts at captive breeding have been mostly unsuccessful. In New Guinea, the lizard is sometimes hunted and skinned by tribesmen to make drums. It is described as an evil spirit that "climbs trees, walks upright, breathes fire, and kills men", yet the local people maintain that it gives warnings if crocodiles are nearby.
Taxonomy
Varanus salvadorii was first described as Monitor salvadorii by Wilhelm Peters and Giacomo Doria in 1878 based on a female specimen with a snout-to-vent length of , and a long tail. It was subordinated to the genus Varanus under the name Varanus salvadorii by George Albert Boulenger in 1885.
There are no formally recognized subspecies of V. salvadorii, but the captive reptiles market distinguishes those from Sorong, Jayapura and Merauke based on the color of their snout and the overall brightness of their color pattern.
Etymology
The generic name, Varanus, is derived from the Arabic waral (), meaning "lizard". The term "monitor" is thought to have come about from confusion between waral and the German , meaning "warning". The term "goanna" came about as a corruption of the name "iguana". The specific name, salvadorii, is derived from a Latinization of Tommaso Salvadori, an Italian ornithologist who worked in New Guinea.
Evolution
The genus Varanus originated in Asia about 40 million years ago (Mya). Around 15 Mya, a tectonic connection between Australia and Southeast Asia allowed the varanids to spread into what is now the Indonesian archipelago.
Based upon DNA sequences of three nuclear and two mitochondrial genes, cladistic analysis identifies the crocodile monitor as a member of a species cluster that includes the lace monitor (V. varius) and the Komodo dragon (V. komodoensis). Morphological considerations suggest that the megalania (V. priscus) was also a member of the group. Monitors apparently colonized Australasia from Asia about 32 Mya; the varius clade then arose about 17 Mya. The Torres Strait separating New Guinea from Australia is less than long, a distance that could have been covered fairly easily with island hopping.
Distribution
The largest of the seven species of monitors found on the island of New Guinea, crocodile monitors occur in both the state Papua New Guinea and the Indonesian region of West Papua. It inhabits the high and low canopies of the lowland rainforests and coastal mangrove swamps, sometimes venturing out of these areas during floods in the rainy seasons. No detailed field investigation data are available for V. salvadorii, so the full extent of its range is unknown. Its remote and generally inaccessible habitat is an obstacle to detailed study of this monitor in its natural habitat.
Biology and morphology
A characteristic feature of the crocodile monitor is its blunt, bulbous snout, which makes it look different from every other monitor on New Guinea, and suggested the common name "tree crocodile". The body of the lizard is dark green with rings of yellow spots. The tail is banded yellow and black and is extremely long.
Its teeth are long, straight, and sharp. Its claws are prominent and strongly curved. Males reach a considerably larger size than females in both weight and length, and also tend to have a more robust head.