[1] It was classified as a separate species, distinct from its close relative, the clouded leopard in mainland Southeast Asia based on a study in 2006.

[1] Between March and August 2005, tracks of clouded leopards were recorded during field research in the Tabin Wildlife Reserve in Sabah.

The population size in the 56 km2 (22 sq mi) research area was estimated to be five individuals, based on a capture-recapture analysis of four confirmed animals differentiated by their tracks.

One explanation for this lower density of about 1.29 individuals per 100 km2 (39 sq mi) might be that on Sumatra it is sympatric with the Sumatran tiger, whereas on Borneo it is the largest carnivore.

[citation needed] Felis diardi was the scientific name proposed by Georges Cuvier in 1823 in honour of Pierre-Médard Diard, who sent a skin and a drawing from Java to National Museum of Natural History, France.

[16] Results of molecular genetic analysis of hair samples from mainland and Sunda clouded leopards showed differences in mtDNA, nuclear DNA sequences, and microsatellite and cytogenetic variation.

This indicates that they diverged between 2 and 0.9 million years ago; their last common ancestor probably crossed a now submerged land bridge to reach Borneo and Sumatra.

[2][3] Molecular, craniomandibular, and dental analysis indicates the Sunda clouded leopard has two distinct subspecies with separate evolutionary histories:[17] Both populations are estimated to have diverged during the Middle to Late Pleistocene.

[17] Sunda clouded leopards being strongly arboreal are forest-dependent, and are increasingly threatened by habitat destruction following deforestation in Indonesia as well as in Malaysia.

[20] There have been reports of poaching of Sunda clouded leopards in Brunei's Belait District where locals are selling their pelts at a lucrative price.

[22] Neofelis diardi is listed on CITES Appendix I, and is fully protected in Sumatra, Kalimantan, Sabah, Sarawak and Brunei.

[23] The Sunda clouded leopard is one of the focal cats of the project Conservation of Carnivores in Sabah based in northeastern Borneo since July 2008.