A Malaysian researcher known for finding new amphibian species said Friday his team had discovered at least one new species of frog in studies he said highlight Borneo\'s rich biodiversity. Indraneil Das of the Universiti Malaysia Sarawak said the brown frog is just 4-5 centimetres (1.6-2.0 inches) long and makes a distinctive high-pitched chirp. His team discovered the frog during an expedition to the rainforests of Mount Singai in the Malaysian state of Sarawak on Borneo island in September 2010. They later found another of the same species in nearby Kubah National Park. Ascertaining whether a species is new is a lengthy scientific process and his discovery remains to be peer-reviewed, he said. \"We heard a call we hadn\'t heard before. It called from under the leaf litter. That\'s probably why no one saw it before,\" Das told AFP. \"It\'s the call that is very distinctive. It was high-pitched, loud and repeated.\" Das said his team had also found several other species of frog that could be previously unknown and was currently investigating them. He now hopes to publish his findings to draw attention to Borneo\'s amazing biodiversity and help promote conservation efforts of its rainforests, currently threatened by logging and other development. Last year, Das made headlines for rediscovering a spindly-legged toad species, the Sambas Stream Toad or Borneo Rainbow Toad, almost 90 years after it was last sighted in the Borneo jungle. The toad was listed as one of the \"World\'s Top 10 Most Wanted Lost Frogs\" in a campaign by Conservation International and another group to encourage scientists worldwide to seek out amphibians not seen for a decade or more. Das has also previously discovered Asia\'s tiniest frog, the size of a pea, in Kubah National Park. The Malaysian states of Sarawak and Sabah occupy the northern portion of Borneo island, which is also shared with Indonesia and Brunei.