New Monitor Lizard Found On Remote Pacific Island

Researchers from the University of Turku have identified a new species of blue-tailed monitor lizard. Separated from its closest relatives by several hundred kilometers like Tom Hanks in "Cast Away," this lizard is isolated on the remote island of Mussau. 

With a body measuring well over one meter long and a tail that is nearly double the size of its body, this monitor lizard is the island's largest native top predator. This new endemic species, subsequently dubbed Varanus semotus, was observed and studied during fieldwork led by Valter Weijola, a graduate student from the University of Turku, Finland. 

Mussau Island is the largest island of St. Matthias Islands in Papua New Guinea, and V. semotus is the first new monitor lizard to be described from the country in over twenty years, according to a news release. 

Monitor lizards play a vital ecological role in many island ecosystems in the southwest Pacific. Due to the remoteness of the St. Matthias Islands, predatory mammals have never inhabited them, which is why these large, active and intelligent lizards reign as top predators and scavengers. 

The new species belongs to the Pacific monitor lineage, which is widely dispersed across almost every island from Moluccas in Indonesia to the eastern Solomon Islands and even Micronesia. 

V. semotus was found in relatively dry coastal vegetation, but researchers believe it is likely that the lizard inhabits remnants of intact forest located towards the interior of the island, too. Massive body and tail length aside, this creature is characterized by a predominately black-colored body with yellow and orange markings. In contrast, its tail shows varying degrees of turquoise to bluish pigmentation. Another distinctive feature includes its pale yellow tongue. 

Based on their findings, researchers suggest adults of the new species prefer eating crabs, small birds that land on the island, and other reptiles and their eggs. 

"Usually monitors like these will eat just about anything they can catch and kill, as well as carcass and turtle eggs when available," Weijola explained in the release. "While young, Pacific monitor lizards are highly secretive and subsist mainly on insects and other small animals."

Further DNA analyses revealed the new reptile is genetically distinct from its relatives from New Guinea and New Britain, and has been isolated for upwards of two million years. 

"Isolation is the keyword here," Weijola added. "It is what has driven speciation and made the South-Pacific region one of the World's biodiversity hotspots. For anything to arrive on Mussau (from New Guinea or New Britain) it would need to cross 250-350 kilometers of open sea, and this doesn't happen frequently. So, once the ancestor arrived, perhaps in the form of a gravid female, the population must have been completely isolated."

Their findings, were recently published in the journal ZooKeys, underscore the number of unique creatures that are restricted in distribution to just one island or island group. 

"Yet, we know relatively little about them," Weijola concluded. "Even large species of reptiles and mammals are regularly being discovered, not to mention amphibians and invertebrates. This is what makes it such a biologically valuable and fascinating region."

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