The white-fronted spider monkey (Ateles belzebuth), also known as the long-haired or white-bellied spider monkey, is an endangered

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 species of spider monkey

Spider monkey

Spider monkeys of the genus Ateles are New World monkeys in the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil...

, a type of New World monkey

New World monkey

New World monkeys are the five families of primates that are found in Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Platyrrhini parvorder and the Ceboidea superfamily, which are essentially synonymous since...

. It is found in the north-western Amazon

Amazon Rainforest

The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...

 in Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, Ecuador

Ecuador

Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, Venezuela

Venezuela

Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

, Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

 and Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, ranging as far south as the lower Ucayali River and as far east as the Branco River

Branco River

The Rio Branco is the principal affluent of the Rio Negro from the north; it is enriched by many streams from the sierras which separate Venezuela and Guyana from Brazil. Its two upper main tributaries are the Urariquira and the Takutu...

. In the past, the Peruvian

Peruvian Spider Monkey

The Peruvian spider monkey is a species of spider monkey that lives not only in Peru, but also in Brazil and Bolivia. At two feet long, they are relatively large among species of monkey, and their strong, prehensile tails can be up to three feet long. Unlike many species of monkey, they have...

, brown

Brown Spider Monkey

The brown spider monkey or variegated spider monkey is a critically endangered species of spider monkey, a type of New World monkey, from northern Colombia and north-western Venezuela. Its taxonomic history has been confusing, and in the past it has been treated as a subspecies of either the...

 and white-cheeked spider monkey

White-cheeked Spider Monkey

The white-cheeked spider monkey, Ateles marginatus, is a species of spider monkey, a type of New World monkey, endemic to Brazil.There are many different varieties of spider monkeys that make their home in the upper levels of the rain forest...

s have been treated as subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of A. belzebuth. As presently defined, the white-fronted spider monkey is monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

. It has a whitish belly and a pale patch on the forehead, which, despite the name white-fronted spider monkey, often is orange-buff

Buff (colour)

Buff is a pale yellow-brown colour that got its name from the colour of buff leather.Displayed on the right is the colour buff.EtymologyAccording to the Oxford English Dictionary, buff as a descriptor of a colour was first used in the London Gazette of 1686, describing a uniform to be "A Red Coat...

. They live in groups of 20 to 40 individuals, splitting into small parties of 1 to 9 when in activity.

Vernacular names include mono prieto, mico prieto and marimonda (Colombia).

Locomotion

All members of Ateles are semi-brachiators, and this species has an intermembral index of 105. They have a fairly dorsally placed scapula to allow for increased mobility involved in brachiation

Brachiation

Brachiation is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms.- Brachiators :...

. Their prehensile tail with a hairless gripping pad at the end also allows for this locomotion, which then means they have increased caudal vertebrae, with about 31 caudal vertebrae as opposed to another platyrrhine like Cebus with only 23 on average. This tail allows for additional grasping of branches, which means there is less lateral movement while brachiating which increases efficiency. The hairless gripping pad of the underside of the tip of their tail is often compared to a finger, since it allows surface gripping. Their curved hands with long metacarpal bones allows for easy brachiation. They do not have an external thumb, which sets them apart from most other primates.

Dentition

Ateles belzebuth has a dental formula of 2.1.3.3. As far as patterns within the teeth, there is a lot of variation but the following are often found within Ateles. Larger incisors and small molars reflect the largely frugivorous diet, with a diastema separating the upper canines from the upper incisors, for the lower incisor. The upper premolars have one to two cusps, with the first premolar having only one cusp, a paracone. The second premolar has a paracone and protocone cusp connected by transverse crest. The third premolar has three cusps, paracone, metacone, and protocone, with the metacone and protocone connected by a crista oblique. There is a recorded hypocone on the third premolar. In the bottom premolars, the first premolar has one cusp although it can be bicuspid. The second and third premolar generally have 2-3 cusps, although the second bottom premolar has an entoconid and hypoconid and the third bottom premolar in belzebuth has five cusps with a small hypoconulid. Upper molars generally have four cusps although the third molar may not have a hypocone (might even have only two cusps). With the bottom molars, there are generally four cusps and a fifth cusp on the third molar.

External links

• ARKive - images and movies of the white-bellied spider monkey (Ateles belzebuth)