White-bellied spider monkey

White-bellied spider monkey[1][2]
Ateles belzebuth in Buenos Aires Zoo.
Conservation status
Endangered  (IUCN 3.1)[2]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Family:	Atelidae
Genus:	Ateles
Species:	A. belzebuth
Binomial name
Ateles belzebuth É. Geoffroy, 1806
White-bellied spider monkey range

The white-bellied spider monkey (Ateles belzebuth), also known as the white-fronted or long-haired spider monkey, is an endangered species of spider monkey, a type of New World monkey. It is found in the north-western Amazon in Colombia, Ecuador, Venezuela, Peru and Brazil, ranging as far south as the lower Ucayali River and as far east as the Branco River.^[2] In the past, the Peruvian, brown and white-cheeked spider monkeys have been treated as subspecies of A. belzebuth. As presently defined, the white-bellied spider monkey is monotypic.^[1] It has a whitish belly and a pale patch on the forehead, which, despite its common name, often is orange-buff.^[3][4] They live in groups of 20 to 40 individuals, splitting into small parties of 1 to 9 when in activity.^[5]

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. 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

Spider monkey in Ecuador.

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.

References

1. Groves, C.P. (2005). Wilson, D.E.; Reeder, D.M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. p. 150. OCLC 62265494. ISBN 0-801-88221-4.
2. Boubli, J.-P., Di Fiore, A., Stevenson, P., Link, A., Marsh, L. & Morales, A.L. (2008). "Ateles belzebuth". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 19 January 2012. Database entry includes justification for why this species is endangered.
3. Sumac Muyu Foundation (2009). Photo of Ateles belzebuth. Flickr
4. raskin227 (2009). Photo of Ateles belzebuth. Flickr
5. Louise Emmons and Francois Feer (1997). Neotropical Rainforest Mammals.

External links

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