The Philippine slow loris (Nycticebus menagensis) is a strepsirrhine primate and a species of slow loris that is native to the north and east coastal areas of the island of Borneo, as well as the Sulu Archipelago in the Philippines. The species was first named as the Bornean slow loris in 1892, but lumped into the widespread Sunda slow loris (N. coucang) in 1952. However, it was promoted to full species status – again as the Bornean slow loris – based on molecular analysis in 2006. In 2013, two former subspecies of the Bornean slow loris were elevated to species status, and a new species—N. kayan—was recognized among the Bornean population. Weighing 265–300 grams (9.3–10.6 oz), it is one of the smallest of the slow lorises, and can be distinguished from other slow lorises by its pale golden to red fur, the lack of markings on its head, and consistent absence of a second upper incisor. Like other slow lorises, it has a vestigial tail, round head, short ears, a curved grooming claw for grooming, and a gland that produces an oily toxin that the animal uses for defense. The Philippine slow loris is arboreal, nocturnal, and occurs in low densities, making it difficult to locate. It is also the least studied of Indonesia's slow lorises. It is found at elevations between 35–100 meters (115–328 ft) in primary and secondary lowland forest, gardens, and plantations. Information about its diet is limited, but it is suspected to be one of the more insectivorous slow loris species, and is also known to eat gum from woody plants. The Bornean slow loris species complex – including the Philippine slow loris – was classified as "Vulnerable" by the International Union for Conservation of Nature (IUCN) in 2008, is included in CITES Appendix I, which prevents international commercial trade, and is protected by Indonesian law. Prior to being divided into four distinct species in 2013, it was found in numerous protected areas within its range, making it the least threatened of the slow lorises. However, since the taxonomic split, it may face a higher risk of extinction. It is sparsely distributed throughout its range and is threatened by illegal wildlife trade, including the exotic pet trade, and habitat loss.
Taxonomy and phylogeny The Bornean slow loris was first described based on specimens collected by Frank S. Bourns and Dean C. Worcester during the Menage Scientific Expedition to the Philippines and Borneo in the early 1890s. The original collection was made between 5 October and 5 November 1891 near Tataan, Tawi-Tawi Island, in the Philippines, however this type specimen is missing as of 2013. The specimens were given to Henry F. Nachtrieb, President of the Minnesota Academy of Sciences and Chairman of the Zoology Department at the University of Minnesota. Nachtrieb was the first to use the name menagensis in 1892, based on a description of the species sent to him by Worcester in 1891. Worcester's progress report included a description of the specimen and an explanation on how they had obtained it:
I now come to the curious mammal of which I enclose description. Shortly before we left for Tawi Tawi the Jesuit priest here, Padre Marche, informed us that just before our arrival he had made a trip to Tawi Tawi, and had bought of the Moros there a curious animal. He said it has the face of a bear, the hands of a monkey, moved like a sloth, and was called "cocam" by the natives ... I believe nothing of this kind has been found in the Philippines before, and it makes an important addition to the rather meager list of Philippine mammals. It is evidently one of the Lemuridae, but as generic characteristics are not given in the book I have, I cannot go farther. Nachtrieb did not assign the name to a specific genus, noting that it was "an undescribed member of the Lemuridae". The following year, the English naturalist Richard Lydekker published the combination Lemur menagensis in The Zoological Record. This makes Lydekker the authority of the species name menagensis, because he was the first to use the specific name in combination with the name of a genus, although some subsequent authors credited other workers. In his influential 1953 book Primates: Comparative Anatomy and Taxonomy, the primatologist William Charles Osman Hill placed all the slow lorises in one species, N. coucang. In 1971, however, Colin Groves recognized the pygmy slow loris (N. pygmaeus) as a separate species, and divided N. coucang into four subspecies, including Nycticebus coucang menagensis. Nycticebus menagensis was elevated to the species level in 2006 when molecular analysis of DNA sequences of the D-loop and the cytochrome b gene demonstrated it to be genetically distinct from N. coucang. The genetic evidence was corroborated by both a previous study (1998) on morphology (based on craniodental measurements) that indicated distinct differences between the subspecies that were consistent with separation at the species level, and a later study (2010) of facial markings. Early in its own taxonomic history, distinguishing coloration patterns and size differences resulted in the division of Nycticebus menagensis into four subspecies: N. m. bancanus, N. m. borneanus, N. m. menagensis, and N. m. philippinus. These later became taxonomic synonyms, although in 2013 N. bancanus and N. borneanus were elevated to species status based on unique facial markings. Furthermore, a new species—N. kayan—was also identified within the Bornean population. The southern Philippine slow lorises (N. m. philippinus or N. philippinus) identified by Spanish zoologist Ángel Cabrera in 1908 remains a synonym of N. menagensis, since the 2013 study was unable to find its type specimen and found no distinguishable characteristics between the two populations. The syntype for N. menagensis was collected by Lydekker in 1893 from the Philippine island of Tawi-Tawi, giving menagensis precedence over philippinus as the name of the species, under the Principle of Priority.
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