The white-fronted surili (''Presbytis frontata'') is a species of

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...

in the family Cercopithecidae, the

Old World monkey Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons ...

s. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the large international island of

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...

, in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

, and possibly

Brunei Brunei ( , ), formally Brunei Darussalam ( ms, Negara Brunei Darussalam, Jawi: , ), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its South China Sea coast, it is completely surrounded by t ...

. Its body is mainly grey-brown, with a distinct white spot on the forehead. Its chin and lower cheeks are greyish. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

is subtropical or tropical dry

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

s. It is threatened by

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

Physical characteristics

The white-fronted surili has a tall

sagittal The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divi ...

crest that leans forward. This species'

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

body is mainly greyish brown and

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

side is yellowish brown in coloration, with a distinct white spot on the forehead. The tail is yellowish grey, with blackish coloration of hands, feet, brow, crown crest and cheeks. There is light colored frontal patch on the crown crest. This species has a sacculated

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

to assist in the breakdown of cellulose and also has enlarged

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary ...

s. The

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s are narrow and the molars have a sharp, high crest. The jaw is deep and the face is short and broad. The thumb is reduced and the hindlimbs are longer than the forelimbs. The average body mass for the adult male is 5.67 kg and for adult females is 5.56 kg. There are two subspecies, ''P. f. frontata'' and ''P. f. nudifrons''. ''P. f. frontata'' is brownish in colour, with darker arms, legs, top and sides of the head and tail. The chin and lower cheeks are greyish. The white spot on the forehead is roughly triangular in shape. ''P. f. nudifrons'' is dark greyish with blackish hands, feet and base of tail. The underparts and the distal end of the tail are paler grey-brown and the throat is white. The white spot on the forehead is rather square compared to ''P. f. frontata'' and is divided by a vertical line of short black hairs.Francis, C.M. & Payne, J. (2005).A field guide to the mammals of Borneo. Malaysia: Sabah Society

Ecology and habitat

This species is diurnal and

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

. It is also primarily a

folivorous In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds.Jones, S., Martin, R., & Pilbeam, D. (1 ...

species, but also consumes fruits and seeds. This species prefers to eat immature leaves to more mature ones. The

group size Many animals, including humans, tend to live in groups, herds, flocks, bands, packs, shoals, or colonies (hereafter: groups) of conspecific individuals. The size of these groups, as expressed by the number of people/etc in a group such as eight g ...

s range from 10 to 15 individuals. ''P. frontata'' can be found in tall lowland and hill dipterocarp forests, not above 300 meters. This species has also been observed in riverine and hill forest.

Distribution

''P. frontata'' is

to Borneo, and restricted to the south-east of Borneo, below 3°N and east of

Barito River The Barito River is the second longest river in Borneo after the Kapuas River with a total length of and with a drainage basin of in South Kalimantan, Indonesia. It originates in the Muller Mountain Range, from where it flows southward in ...

. It was recorded in the east between the Kayan River and

Banjarmasin ) , translit_lang1 = Other , translit_lang1_type1 = Jawi , translit_lang1_info1 = بنجر ماسين , settlement_type = City , motto = ''Kayuh Baimbai'' ( Banjare ...

in the south. Meanwhile, ''P. f. nudifrons'' was recorded from central Sarawak between the upper

Rajang River The Rajang River ( ms, Batang Rajang) is a river in Sarawak, northwest Borneo, Malaysia. The river originates in the Iran Mountains, flows through Kapit, and then towards the South China Sea. At approximately , the river is the seventh-longest i ...

and upper Batang Lupar, including

Lanjak Entimau Wildlife Sanctuary Lanjak Entimau Wildlife Sanctuary is a large protected area on the island of Borneo in Sarawak, Malaysia. It is significant for orangutan conservation. Together with Batang Ai National Park these protected areas host an estimated 1,400 oranguta ...

Social behaviour and communication

The white-fronted surili moves through the forest quadrupedally. This species also moves through the forest by leaping. In the population, solitary males have been observed in this species. For communication, the males use loud calls to demarcate the group’s territory. There is also tactile communication, which is social grooming. This is when one individuals groom another to reinforce the bonds between individuals. For reproduction, they only gives birth to a single offspring.

Threats and conservation

This species is listed as vulnerable because the population trends are decreasing to more than 30% over the last three generation (approximately 30 years). This is due to the hunting for the meat and traditional medicine, as well as habitat loss. The forest habitat is being loss rapidly, especially due to oil palm plantations and other anthropogenic habitats. For conservation, this species is protected Indonesian law and is totally protected in Sarawak. There are at least seven protected areas known, which only one in Malaysia, Lanjak-Entimau Wildlife Sanctuary.

References

{{Taxonbar, from=Q936878 white-fronted surili Endemic fauna of Borneo Primates of Indonesia Mammals of Borneo Mammals of Malaysia Mammals of Brunei Vulnerable fauna of Asia white-fronted surili Taxonomy articles created by Polbot Taxa named by Salomon Müller