Mussau Island is one of the northernmost islands in Papua New Guinea. Not many animals make it out there, including biologists. That's why this metre-long monitor lizard has been stalking the island for at least a million years before anyone knew it existed. Pacific islands are notoriously low on mammals, and those mammals that do live there tend to be small and unobtrusive. These animals pluck the grass, dig in the earth and lure biologists, like the scientists from University of Turku, Finland, who spent 2012 scrambling around Mussau Island. Mussau has a vast amount of animals that have yet to be catalogued, so the scientists were expecting to find something -- just not a metre-long lizard. They published a description of the animal in Zookeys.
The lizard lives in the dry coastal forests on the edges of Mussau. Juveniles are elusive, but as an adult the lizard is clearly unconcerned with standing out. It has a black body, bright yellow dot-like markings, a blue tail and a pale yellow tongue. It's a monitor lizard, the same family of lizards that include the famous Komodo dragon.
This lizard, now called Varanus semotus, is less of a threat to humans than the dragon. It wanders the island eating crabs, other reptiles, small birds and eggs. It's likely that the juveniles eat insects and perhaps vegetation. Monitors will eat what they can get.
The researchers don't know how this particular lizard ended up on Mussau, but they know it happened a long time ago. Genetic studies show that it's lived in isolation from its fellow monitors for between one and two million years. During that time it's been the island's largest land-living predator.
Unfortunately, now it has competition. Though the scientists expect that the monitor lives in the intact forests in the interior of the island, they suspect it can't survive in deforested habitat. And they're worried about how it will deal with recently-arrived cane toads. With luck, we'll be seeing more of this predator, not less.
Image credit: Valter Weijola