A meter-long, blue-tailed lizard had been stalking the Mussau Island in Papua New Guinea for 2 million years before being discovered.
Not many animals live on the Pacific islands. Local animal residents are often inconspicuous and small, and can easily evade biologists.
The island is teeming with uncatalogued species. So in 2012, scientists from the University of Turku in Finland searched Mussau Island for new finds and they did.
They named the new lizard species Varanus semotus and published the discovery in the website Zookeys. Its black body has bright yellow spots. With a pale yellow tongue and a blue tail, this monitor lizard stems from the line of Komodo dragons and lives in the dry forests on the island's edges.
Study lead Valter Weijola said that normally, monitors like the Varanus semotus would eat anything they can catch. The investigation revealed that the blue-tailed lizard feeds on crabs, small birds and its eggs. It also eats other reptiles, at least for the adult ones. The younger lizards probably feed on vegetation and insects.
While the researchers are uncertain how the Varanus semotus came to the Mussau Island, they are certain the arrival happened millions of years ago. Genetic analysis revealed that the new lizard's isolation from fellow monitors is roughly 1 to 2 million years old, which makes them the island's biggest land-based predator.
"Isolation is the keyword here. It is what has driven speciation and made the South-Pacific region one of the World's biodiversity hotspots," added Weijola, a graduate student at the University of Turku. Weijola added that these islands are full of rare species with restricted distribution.
If species want to go to the Mussau Island, it requires crossing a 250- to 350-kilometer (155- to 217-mile) open sea from New Britain or New Guinea. These voyages don't happen frequently, especially among animals.
"So, once the ancestor arrived, perhaps in the form of a gravid female, the population must have been completely isolated," said Weijola.
Unfortunately for these island kings, the recent arrival of cane toads can affect their lifestyle. Scientists are worried that they wouldn't survive in a deforested landscape.
