Scientists have discovered that the clouded leopards that prowl the islands of Sumatra and Borneo are very different to those that inhabit mainland southeast Asia. Recent genetic analysis shows that they are so different, in fact, that they should be classified as a separate species.

The study revealed that the leopards of Sumatra and Borneo diverged from the mainland cats over one million years ago. Since then, they have developed dozens of genetic differences. The clouded leopards of Sumatra and Borneo have darker fur than their mainland cousins as well as more distinct spots and stripes along their backs.

The physical differences between the species are backed by genetic evidence. When scientists from the US National Cancer Institute compared DNA samples from the mainland and island clouded leopard populations, they found about 40 nucleotide differences. This level of genetic variation is comparable to that observed for other large Panthera species. For example, lions and leopards differ by 56 nucleotides.

The clouded leopard was first described in 1821 by a British naturalist named Edward Griffith. At that time, no notice was made of the physical differences between the mainland and island populations (and it was still years before genetic analysis was available to scientists). So mainland and island leopards were combined as one species under the scientific name of Neofelis nebulosa. Today, in light of the genetic evidence, the mainland cat will retain the scientific name Neofelis nebulosa but the island populations will be classified under the new name, Neofelis diardi.

Find out more:

• Borneo Clouded Leopard Classified as New Species (Clouded Leopard Project)
• Buckley-Beason, Valerie A. et. al. Molecular Evidence for Species-Level Distinction in Clouded Leopards. Current Biology 16, 2371-2376, December 5, 2006.
• Borneo's Clouded Leopard Identified as New Cat Species (WWF)
• Island Leopard Deemed New Species (BBC News)
• Clouded Leopards (WWF)
• Heart of Borneo Forests (WWF)

Photo © Inhaus Creative / iStockphoto. Mainland clouded leopard (Neofelis nebulosa).