Slow Loris vs Pygmy Slow Loris: 6 Key Differences

Key Takeaways

The pygmy slow loris was reclassified into its own genus, Xanthonycticebus, in 2022, separate from the eight Nycticebus species.

Pygmy slow lorises are smaller (~15–25 cm, ~120–500 g) than other slow lorises, which reach up to ~38 cm and ~2,100 g.

The pygmy slow loris lives in Vietnam, Laos, Cambodia and southern China, and commonly bears twins.

Both groups are nocturnal, gum-eating, venomous and threatened, all listed on CITES Appendix I.

The pygmy slow loris is Endangered; other slow lorises range from Vulnerable to Critically Endangered.

Slow loris vs pygmy slow loris: same family, separate genus

All slow lorises are easy to confuse — round eyes, slow movements, a venomous bite. But the pygmy slow loris is distinct enough that scientists gave it its own genus in 2022. Here is how the smaller specialist differs from its larger relatives.

1. Genus and classification

The eight "true" slow lorises sit in the genus Nycticebus. The pygmy slow loris was reclassified in 2022 as Xanthonycticebus pygmaeus on the basis of genetic and physical differences — so it is now the lone member of its own genus.

2. Size and weight

Size is the quickest tell. Across Nycticebus, head-body length runs roughly 18–38 cm and weight from about 265 g (Bornean) up to around 2,100 g (Bengal). The pygmy slow loris is smaller, around 15–25 cm and roughly 120–500 g.

3. Range

The pygmy slow loris is found in Vietnam, Laos, Cambodia and southern China — the eastern edge of the slow loris world. Other species range across Indonesia, Malaysia, Thailand, India, Bangladesh and beyond.

4. Reproduction

Twins are common in the pygmy slow loris, whereas the larger species usually carry a single infant per birth. Female pygmy lorises can also reach sexual maturity early, at around nine months.

5. Seasonal biology

The pygmy slow loris is notable for marked seasonal changes tied to its more variable, sometimes cooler habitat, including shifts in activity and body condition — adaptations less pronounced in its tropical-forest relatives.

6. What they share

Despite the split, the similarities run deep. Both are nocturnal, arboreal, gum-loving exudativores; both are the only venomous primates, with the same elbow-gland-plus-saliva system; and both are threatened. The pygmy slow loris is listed as Endangered, while other species range from Vulnerable to Critically Endangered, and all sit on CITES Appendix I.

For the full taxonomy, diet and conservation breakdown of every species, see our slow loris species guide.

WARN's partners care for trafficked lorises of several species, including pygmy slow lorises seized from the trade. Supporting the slow loris appeal helps fund their recovery.

Read the full Slow loris wildlife guide for the facts, IUCN status and conservation context — or donate to WARN to help fund the local partners protecting this species.

Frequently Asked Questions

What is the difference between a slow loris and a pygmy slow loris?

The pygmy slow loris is smaller (around 15–25 cm and 120–500 g) and was reclassified into its own genus, Xanthonycticebus, in 2022, while the other eight slow lorises stay in Nycticebus. The pygmy species lives in Vietnam, Laos, Cambodia and southern China and often bears twins, but both share a venomous bite, a gum-rich diet and nocturnal, arboreal habits.

Is the pygmy slow loris still a slow loris?

Yes. Despite being moved to its own genus, Xanthonycticebus, in 2022, the pygmy slow loris is still a slow loris within the family Lorisidae. The change reflects genetic and physical distinctions, not a removal from the slow loris group.

Are pygmy slow lorises venomous too?

Yes. Like all slow lorises, the pygmy slow loris produces venom using a gland near the elbow that is activated when mixed with saliva, and it is listed on CITES Appendix I, meaning commercial international trade is banned.