Slow loris
Slow lorises are a group of several species of nocturnal strepsirrhine primates that make up the genus Nycticebus. Found in Southeast Asia and nearby 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, Bengal slow loris, Javan slow loris, Philippine slow loris, Bangka slow loris, Bornean slow loris, Kayan River slow loris and Sumatran slow loris. A ninth species, the pygmy slow loris, 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 lorises have a round head, a narrow snout, large eyes, and a variety of distinctive coloration patterns that are species-dependent. Their arms and legs are nearly equal in length, and their torso is long and flexible, allowing them to twist and extend to nearby branches. The hands and feet of slow lorises have several adaptations that give them a pincer-like grip and enable them to grasp branches for long periods of time. Slow lorises have a toxic bite, a trait rare among mammals and unique among the primates. The toxin is obtained by licking a sweat gland on their arm, and the secretion is activated by mixing with saliva. Their toxic bite, once thought to be primarily a deterrent to predators, has been discovered to be primarily used in disputes within the species.
The secretion from the arm contains a chemical related to cat allergen, but may be augmented by secondary toxins from the diet in wild individuals. Slow lorises move slowly and deliberately, making little or no noise, and when threatened, they stop moving and remain motionless. Their only documented predators—apart from humans—include snakes, changeable hawk-eagles and orangutans, although cats, viverrids and sun bears are suspected. Little is known about their social structure, but they are known to communicate by scent marking. Males are highly territorial. Slow lorises reproduce slowly, and the infants are initially parked on branches or carried by either parent. They are omnivores, eating small animals, fruit, tree gum, and other vegetation.
Each of the slow loris species that had been identified prior to 2012 is listed as either "Vulnerable" or "Endangered" on the IUCN Red List. The three newest species are yet to be evaluated, but they arise from 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. 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.
Taxonomy and systematics
Although many previous classifications recognized as few as a single all-inclusive species, there are now at least eight that are considered valid:Other than the pygmy slow loris in sister genus Xanthonycticebus, 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.
Evolutionary history
Slow lorises are strepsirrhine primates and are related to other living lorisoids, such as the pygmy slow loris, slender lorises, pottos, false pottos, angwantibos, and galagos, and to the lemurs of Madagascar. They are most closely related to the pygmy slow loris, followed by the slender lorises of South Asia, the angwantibos, pottos and false pottos of Central and West Africa. Lorisoids are thought to have evolved in Africa, where most living species occur; later, one group may have migrated to Asia and evolved into the slender and slow lorises of today.Lorises first appear in the Asian fossil record in the Miocene, with records in Thailand around 18 million years ago and in Pakistan 16 mya. 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. The species is named ? Nycticebus linglom, using open nomenclature.
Several lorises are found in the Siwalik deposits of Pakistan, including Nycticeboides and Microloris; they date from 16 to 8 mya Most are small, but an unnamed form dating to 15–16 mya is comparable in size to the largest living slow lorises. Molecular clock analysis suggests that slow lorises may have started evolving into distinct species about 10 mya. They are thought to have reached the islands of Sundaland when the Sunda Shelf was exposed at times of low sea level, creating a land bridge between the mainland and islands off the coast of Southeast Asia.
Discovery and taxonomy
The earliest known mention of a slow loris in scientific literature is from 1770, when Dutchman Arnout Vosmaer described a specimen of what we know today as N. bengalensis that he had received two years earlier. The French naturalist Georges-Louis Leclerc, Comte de Buffon, later questioned Vosmaer's decision to affiliate the animal with sloths, arguing that it was more closely aligned with the lorises of Ceylon and Bengal. The word "loris" was first used in 1765 by Buffon as a close equivalent to a Dutch name, loeris. This etymology was later supported by the physician William Baird in the 1820s, who noted that the Dutch word loeris signified "a clown".In 1785, the Dutch physician and naturalist Pieter Boddaert was the first to officially describe a species of slow loris using the name Tardigradus coucang. This species was based on the "tailless maucauco" described by Thomas Pennant in 1781, which is thought to have been based on a Sunda slow loris, and on Vosmaer's description of a Bengal slow loris. Consequently, there has been some disagreement over the identity of Tardigradus coucang; currently the name is given to the Sunda slow loris. The next slow loris species to be described was Lori bengalensis, named by Bernard Germain de Lacépède in 1800.
In 1812, Étienne Geoffroy Saint-Hilaire named the genus Nycticebus, naming it for its nocturnal behavior. The name derives from the, genitive form of νύξ, and κῆβος. Geoffroy also named Nycticebus javanicus in this work. Later 19th-century authors also called the slow lorises Nycticebus, but most used the species name tardigradus for slow lorises, until mammalogists Witmer Stone and James A. G. Rehn clarified in 1902 that Linnaeus's name actually referred to a slender loris.
Several more species were named around 1900, including Nycticebus menagensis by Richard Lydekker in 1893 and Nycticebus pygmaeus by John James Lewis Bonhote in 1907. However, in 1939 Reginald Innes Pocock consolidated all slow lorises into a single species, N. coucang, and in his influential 1953 book Primates: Comparative Anatomy and Taxonomy, primatologist William Charles Osman Hill also followed this course. In 1971 Colin Groves recognized the pygmy slow loris as a separate species, and divided N. coucang into four subspecies, while in 2001 Groves opined there were three species, and that N. coucang had three subspecies.
File:Slow Loris.jpg|thumb|The Kayan River slow loris was distinguished from N. menagensis in 2012.
In 2006, the Bornean slow loris was elevated to the species level based on molecular analysis of DNA sequences of the D-loop and the cytochrome b gene. In 2008, Groves and Ibnu Maryanto confirmed the promotion of the fifth species, the Javan slow loris, to species status, a move that had been suggested in previous studies from 2000. They based their decision on an analysis of cranial morphology and characteristics of pelage. Species differentiation was based largely on differences in morphology, such as size, fur color, and head markings.
To help clarify species and subspecies boundaries, and to establish whether morphology-based classifications were consistent with evolutionary relationships, the phylogenetic relationships within the genus Nycticebus were investigated by Chen and colleagues using DNA sequences derived from the mitochondrial markers D-loop and cytochrome b. Previous molecular analyses using karyotypes, restriction enzymes, and DNA sequences were focused on understanding the relationships between a few species, not the phylogeny of the entire genus. The analyses published in 2006 by Chen and colleagues' proved inconclusive, although one test suggested that N. coucang and N. bengalensis apparently share a closer evolutionary relationship with each other than with members of their own species, possibly due to introgressive hybridization since the tested individuals of these two taxa originated from a region of sympatry in southern Thailand. This hypothesis was corroborated by a 2007 study that compared the variations in mitochondrial DNA sequences between N. bengalensis and N. coucang, and suggested that there has been gene flow between the two species.
In 2012, two taxonomic synonyms of N. menagensis—''N. bancanus and N. borneanus—were elevated to species status, and a new species—N. kayan—was also distinguished from the same. Rachel Munds, Anna Nekaris and Susan Ford based these taxonomic revisions on distinguishable facial markings. With that, the N. menagensis species complex that had been collectively known as the Bornean slow loris became four species: the Philippine slow loris, the Bornean slow loris, the Bangka slow loris, and the Kayan River slow loris.
Nekaris and Nijman combined morphological, behavioural, karyotypical and genetic data and suggested that the pygmy slow loris is best placed in its own genus, Xanthonycticebus.''