The only specimen of the monitor lizard Lesson collected on New Ireland never reached its destination in France and was not studied in detail.
Since then, it has been believed that the monitor lizards on New Ireland are the common mangrove monitors (Varanus indicus).
But the new study confirms that the monitor lizards on New Ireland are a distinct species.
On an island in Papua New Guinea, scientists say they have rediscovered a species of monitor lizard thought to be “lost” to science since the 1800s.
The medium-sized lizard was first discovered on the island of New Ireland in 1823 by French naturalist René Lesson, who named the species Varanus douarrha. According to Lesson, douarrha was the local word for the monitor lizard in Port Praslin, located at the southern end of New Ireland.
The only specimen he collected, however, never reached its destination in France and was not studied in detail. It was likely lost in a shipwreck off the Cape of Good Hope.
“Since then, it has been believed that the monitor lizards on New Ireland belong to the common mangrove monitor (Varanus indicus) that occurs widely in northern Australia, New Guinea and surrounding islands,” lead author Valter Weijola, a researcher at the Biodiversity Unit of the University of Turku, Finland, said in a statement.
However, when Weijola collected and examined monitor lizards on New Ireland during field surveys in 2012, he found that the lizards are distinct from the common mangrove monitor and are a separate species. His team’s findings were published in the Australian Journal of Zoology.
“New morphological and genetic studies confirmed that the monitor lizards of New Ireland have lived in isolation for a long time and developed into a separate species,” Weijola said.
The newly described Varanus douarrha is black with yellow spots, and can grow to about 1.3 meters (~4.3 feet) in length. It is the only large native predator currently known to live on New Ireland, the authors write in the paper.
Hunting of monitor lizards is common on New Ireland. But current levels of hunting are not likely to pose a threat to the long-term survival of the species, the researchers add.
Last year, Weijola and his team discovered a new species of monitor lizard on Mussau, another island in Papua New Guinea. The turquoise-tailed lizard, Varanus semotus, is thought to be the only known large-sized predator and scavenger on the island.
“Together, these two species have doubled the number of monitor lizard species known to occur in the Bismarck Archipelago [of which New Ireland is a part] and proved that there are more endemic vertebrates on these islands than previously believed,” said Weijola.
- Valter Weijola, Fred Kraus, Varpu Vahtera, Christer Lindqvist, Stephen C. Donnellan. Reinstatement of Varanus douarrha Lesson, 1830 as a valid species with comments on the zoogeography of monitor lizards (Squamata:Varanidae) in the Bismarck Archipelago, Papua New Guinea. Australian Journal of Zoology, 2017; DOI: 10.1071/ZO16038