The Thai record is based on a single tooth that most closely resembles living slow lorises and that is tentatively classified as a species of Nycticebus. Nycticebus linglom, using open nomenclature (the preceding "?" indicates the tentative nature of the assignment).The three newest species are yet to be evaluated, but they arise from (and further reduce the ranks of) what was thought to be a single "vulnerable" species.All four of these are expected to be listed with at least the same, if not a higher-risk, conservation status.Later 19th-century authors also called the slow lorises Nycticebus, but most used the species name tardigradus (given by Linnaeus in 1758 in the 10th edition of Systema Naturæ) for slow lorises, until mammalogists Witmer Stone and James A. Rehn clarified in 1902 that Linnaeus's name actually referred to a slender loris. This hypothesis was corroborated by a 2007 study that compared the variations in mitochondrial DNA sequences between N. coucang, and suggested that there has been gene flow between the two species. borneanus—were elevated to species status, and a new species—N. Rachel Munds, Anna Nekaris and Susan Ford based these taxonomic revisions on distinguishable facial markings.while in 2001 Groves opined there were three species (N. In 2012, two taxonomic synonyms (formerly recognized as subspecies) of N. Similar to the slender lorises, the fur around and directly above the eyes is dark.Unlike the slender lorises, however, the white stripe that separates the eye rings broadens both on the tip of the nose and on the forehead while also fading out on the forehead.and possess a reflective layer, called the tapetum lucidum, that improves low-light vision.
Slow lorises (genus Nycticebus) are strepsirrhine primates and are related to other living lorisoids, such as slender lorises (Loris), pottos (Perodicticus), false pottos (Pseudopotto), angwantibos (Arctocebus), and galagos (family Galagidae), and to the lemurs of Madagascar.
All slow lorises are threatened by the wildlife trade and habitat loss.
Their habitat is rapidly disappearing and becoming fragmented, making it nearly impossible for slow lorises to disperse between forest fragments; unsustainable demand from the exotic pet trade and from traditional medicine has been the greatest cause for their decline.
Their only documented predators—apart from humans—include snakes, changeable hawk-eagles and orangutans, although cats, civets and sun bears are suspected.
Little is known about their social structure, but they are known to communicate by scent marking. Slow lorises reproduce slowly, and the infants are initially parked on branches or carried by either parent.