Slow lorises are a group of several species of nocturnal strepsirrhine primates that make up the genus Nycticebus. Found in Southeast Asia and bordering areas, they range from Bangladesh and Northeast India in the west to the Sulu Archipelago in the Philippines in the east, and from Yunnan province in China in the north to the island of Java in the south. Although many previous classifications recognized as few as a single all-inclusive species, there are now at least eight that are considered valid: the Sunda slow loris (N. coucang), Bengal slow loris (N. bengalensis), Javan slow loris (N. javanicus), Philippine slow loris (N. menagensis), Bangka slow loris (N. bancanus), Bornean slow loris (N. borneanus), Kayan River slow loris (N. kayan) and Sumatran slow loris. A ninth species, the pygmy slow loris (X. pygmaeus), was recently moved to the new genus Xanthonycticebus. After the pygmy slow loris, the group's closest relatives are the slender lorises of southern India and Sri Lanka. Their next closest relatives are the African lorisids, the pottos, false pottos, and angwantibos. They are less closely related to the remaining lorisoids, and more distantly to the lemurs of Madagascar. Their evolutionary history is uncertain since their fossil record is patchy and molecular clock studies have given inconsistent results.
Slow loris
The Kayan River slow loris (N. kayan) was distinguished from N. menagensis in 2012.
The skull of the Sunda slow loris
Coloration patterns around the eyes differ between the slender lorises (middle two) and the slow lorises (top and bottom).
Strepsirrhini or Strepsirhini is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Collectively they are referred to as strepsirrhines. Also belonging to the suborder are the extinct adapiform primates which thrived during the Eocene in Europe, North America, and Asia, but disappeared from most of the Northern Hemisphere as the climate cooled. Adapiforms are sometimes referred to as being "lemur-like", although the diversity of both lemurs and adapiforms does not support this comparison.
Strepsirrhini
Early primates possessed adaptations for arboreal locomotion that enabled maneuvering along fine branches, as seen in this slender loris.
Notharctus, a type of North American adapiform, resembled lemurs but did not give rise to them.
The suborder Strepsirrhini was proposed by É. Geoffroy in 1812.