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Three new animal species – two frogs and a gecko – have been discovered on a remote island in Australia’s north.
The animals were found on Dauan Island, a 3 sq km island in the far northern Torres Strait that is dominated by boulder fields.
Conrad Hoskin, an associate professor and terrestrial ecologist at James Cook University, described the new species after a research expedition to Dauan – the northernmost point of the Great Dividing Range.
“When you approach it, it just looks like a big triangle sticking out of the sea, and as you get closer, you realise you’re looking at … car- and house-sized granite boulders piled up.
“We hiked up into all those boulder fields and found the gecko quickly,” Hoskin said, having been tipped off by researcher Alexander Davies, who suspected the island had reptiles not yet known to science.
Named Nactus simakal, the Dauan Island gecko has a banded pattern and long legs.
“On the second night, when it was raining, there were these two really distinct frog calls,” Hoskin said. “Sure enough, they were species new to science.”
The smaller of the two frogs, Choerophyrne koeypad (koeypad meaning “rocky mountain), has oversized toe pads and a high-pitched call – “like a metallic tapping noise”, Hoskin said.
“It’s very small, about the size of my fingernail, but super loud.”
Its toe pads enable it to climb up on to high boulder surfaces and vegetation.
The larger frog, Callulops gobakula (gobakula meaning “boulders”), has a croaking call similar to that of a green tree frog, and lives in the cracks between boulders.
The two frogs belong to the microhylid family, and are believed to be terrestrial breeders, meaning that frogs hatch directly from laid eggs. Other microhylid species in New Guinea and Australia breed in a similar manner, bypassing the tadpole stage.
Hoskin said the new frogs’ closest relatives were up in the central ranges of New Guinea. “A lot of the southern plains of New Guinea are a bit … drier,” he said. “These two frogs have only survived on this island because of those deep boulder fields that buffer them from the heat.
“All three species will certainly only be on Dauan Island. There’s no other bouldery habitat anywhere nearby, either on the other islands or on the southern New Guinea plains.”
Torenzo Elisala, councillor for Dauan Island, said the discoveries “highlight how special our island is”.
“Our community has been tucked away in the Guda Maluilgal nation for millennia, sharing the spiritual connection from flora to fauna to that of our ancestors who lived on these lands before us,” he said.
“These discoveries are exciting to learn more about science and add to the tourism potential of the island.”
Hoskin described the new species in two papers published in the journal Zootaxa.
