No animal species are known to be found only in Brunei.
Understand that political borders rarely match how animals live. Brunei is a small part of the island of Borneo. Most wildlife in Brunei also lives in neighboring Sabah, Sarawak, and Kalimantan. Ask for strict endemism (species found inside Brunei and nowhere else) and you get no clear examples.
Note that the criterion is very narrow. Species ranges follow habitat, not borders. Brunei shares the same forests, rivers, and coasts as the rest of Borneo. Taxonomy and surveys also matter: some populations in Brunei may be unique subspecies or poorly studied groups, but that does not make a species Brunei‑only. Many species that people expect are instead Borneo endemics that occur in Brunei (for example, the proboscis monkey, Nasalis larvatus, and Müller’s gibbon, Hylobates muelleri). These are best described as Borneo endemics present in Brunei, not Brunei‑exclusive species.
Check related categories instead. Look for (1) Borneo endemics that live in Brunei, (2) species with Brunei‑restricted subspecies or populations, and (3) notable resident species and their conservation status. Explore authoritative sources such as IUCN, GBIF, and BirdLife for species lists and range maps.
