An international team of researchers has found and re-described a species of monitor lizard, Varanus douarrha, from the island of New Ireland in the Bismarck Archipelago, northeast of Papua New Guinea.
Varanus douarrha was described from a single specimen obtained by French naturalist René Lesson in Port Praslin at the southern end of New Ireland during his work on the La Coquille exploration ship in 1823.
“Considering that no measurements are provided in Lesson’s 1830 description it appears questionable whether the type specimen ever reached Europe for closer inspection,” the researchers said.
“Three boxes of La Coquille’s South American and Pacific collections were sent toward France with the ship’s surgeon Prosper Garnot, who had fallen ill with dysentery. First, as far as Mauritius on the convict ship Castle Forbes, and from there onward with the King George IV, which shipwrecked at the Cape of Good Hope 15 July 1824, and all the collections were lost.”
Since then, it has been believed that monitor lizards on New Ireland belong to the mangrove monitor (Varanus indicus).
“However, 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,” said team member Valter Weijola, a researcher in the Department of Biology at the University of Turku, Finland, and lead author of a report on Varanus douarrha in the Australian Journal of Zoology.
The discovery is particularly interesting as most of the endemic species to New Ireland disappeared thousands of years ago as humans colonized the island.
“Varanus douarrha can grow to over 4.3 feet (1.3 m) in length and, according to current information, it is the only surviving large species endemic to the island,” Weijola said.
“Based on bone discoveries, we now know that a large rat species and several flightless birds have lived in the area.”
“In that way it can be considered a relic of the historically richer fauna that inhabited the Pacific islands.”
“These medium-sized Pacific monitors are clearly much better at co-existing with humans than many of the birds and mammals have been.”
Valter Weijola et al. 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, published online April 26, 2017; doi: 10.1071/ZO16038