The castaway: New monitor lizard fills top-order predator role on remote Pacific island

Date: February 24, 2016

Source: Pensoft Publishers

Separated by several hundred kilometres from its next of kin, a new species of blue-tailed monitor lizard unique to the remote Mussau Island has been described. Unknown to science until recently and formally termed the "isolated," it is the only large-sized land-living predator and scavenger native to the island.

Dubbed a "biogeographical oddity" by its discoverers, led by Valter Weijola, a graduate student from the University of Turku, Finland, the lizard species is also the first new monitor lizard to be described from the country of Papua New Guinea in over twenty years. The finding was published in the open-access journal ZooKeys.

Monitors play an important ecological role in many island ecosystems in the southwest Pacific. Predatory mammals have never colonized the region due to the isolation of these islands. Instead, these large, active and intelligent lizards fill the role of top-predators and scavengers. The Pacific monitor lineage to which the new species belongs have been so successful at oversea dispersal that a number of different species now occupy almost every island from the Moluccas in Indonesia to the eastern Solomon Islands and even Micronesia.

The new endemic species was observed and studied during fieldwork by Weijola and local assistants in the relatively dry coastal vegetation of Mussau, but it is likely that it also persist in the remnants of intact forest in the interior of the island.

The formally described female lizard, or holotype, measures 1 m with the tail being one and and a half times the length of the dominantly black-coloured body covered with yellow and orange markings. The tail of the adults shows varying degrees of turquoise to bluish pigmentation. Another distinctive feature for the species is the pale yellow tongue, which is a trait shared only by three other species of Pacific monitors. The new species is known to eat crabs, other reptiles and their eggs, and small birds.

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