Hoolock gibbon

Hoolock gibbons
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hylobatidae Genus: Hoolock Mootnick & Groves, 2005
Species
Hoolock hoolock Hoolock leuconedys

Hoolock gibbon is the common name for any of the arboreal, tailless, Asian apes belonging to the gibbon genus Hoolock, characterized by long limbs, thick and shaggy hair, a tuft of hair in the anogenital region, and males that are black with a white strip above the eyes. Also known as hoolocks and the white-browed gibbon, two extant species of hoolock gibbons are recognized currently: H. hoolock (western hoolock gibbon) and H. leuconedys (eastern hoolock gibbon), distinguished, among other characters, by H. hoolock having a white unibrow and H. leuconedys having two distinct white eyebrows. However, the recognition of two species, and the Hoolock genus itself, are recent developments, and in some taxonomies these two primate groups continue to be considered as subspecies within the one species of H. hoolock and traditionally the hoolock gibbons were placed at the subgenus level of the genus Hylobates.

Overview

The hoolock gibbons (genus Hoolock) are two primate species from the family of the gibbons, Hylobatidae, of the ape superfamily Hominoidea. Gibbons, which also are known as "lesser apes to distinguish them from members of the family Hominidae (great apes), generally have four recognized genera, Hylobates, ''Hoolock, Symphalangus, Nomascus.

However, the classification of gibbons has changed considerably over the years. Classically, all gibbons, including the hoolock gibbons, were classified in the genus Hylobates, as can be seen in the taxonomies of Groves (1997), Goodman (1999), Wilson and Reeder (1993), Nowark and Walker (1991), and Napier and Napier (1985). Goodman (1999) further separated the siamangs into their own genus, Symphalangus, but the other taxonomies all included the siamangs in the genus Hylobates. Bunopithecus was recognized as the hoolock subgenus distinct from other gibbon subgenera. However, molecular evidence indicated that the distance among the various subgenera waws substantial and the subgenera were elevated to full genus status, making for the four currently recognized genera. Geissmann (2006a) reports that "recognition of the four groups as full genera is now widespread."

However, the type species for Bunopithecus is Bunopithecus sericus, an extinct gibbon or gibbon-like ape from Sichuan, China. Very recent investigations have shown that the hoolocks are not closely related to B. sericus and so have been placed in their own genus, Hoolock. The four extant genera (formerly subgenera) are recognized based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50) (Mootnick and Groves 2005; Geissmann 2006b).

The traditional taxonomy also recognized the hoolock is one species, first Hylobates

In the process, the two subspecies of hoolocks have been raised to species level (Moontick and Groves 2005; Groves 2005).

However, in recent years, the four subgenera have been raised to the level of genera, and

One unique aspect of gibbon physiology contributing significantly to its remarkable brachiation capabilities is the ball and socket joint forming the wrist connecting the hand with the forearm. In comparison with the wrist of humans as an aid for swinging from hand to hand, the gibbon's ball-joint wrist greatly reduces both the amount of energy needed in the upper arm and torso and the stress on the shoulder joint. Brachiation in gibbons is further aided by their long hands and feet, with a deep cleft between the first and second digits of their hands. Their fur is usually black, gray, or brownish, often with white markings on hands, feet, and face. Some species have an enlarged throat sac, which inflates and serves as a resonating chamber when the animals call. This structure is enormous in a few species, equaling the size of the animal's head.

Gibbon skulls resemble those of the great apes, with very short rostra, enlarged braincases, and large orbits that face forward. Gibbons have the typical nose of catarrhine primates with nostrils that are close together and face forward and slightly downward. They lack cheek pouches and their stomach is not sacculated. Their teeth also are similar to the great apes, with molars that are bunodont and lack lophs. The upper molars usually have a cingulum, which is sometimes large. The canines are prominent but not sexually dimorphic. The dental formula is:

Dentition
2, 1, 2, 3
2, 1, 2, 3

Gibbons are social animals and form pair bonds.

Hoolocks are the second largest of the gibbons, after the Siamang. They reach a size of 60 to 90 cm and weigh 6 to 9 kg. The sexes are about the same size, but they differ considerably in coloration: males are black colored with remarkable white brows, while females have a grey-brown fur, which is darker at the chest and neck. White rings around the eyes and around the mouth give their face a mask-like appearance.

The range of the hoolocks is the most northwestern of all the gibbons, extending from Assam in North-East India, to Myanmar. Small populations (in each case few hundred animals) live also in the eastern Bangladesh and in southwest China. Like the other gibbons, they are diurnal and arboreal, brachiating through the trees with their long arms. They live together in monogamous pairs, which stake out a territory. Their calls serve to locate family members and ward off other gibbons from their territory. Their diet consists mainly of fruits, insects and leaves.

Young hoolocks are born after a seven month gestation, with a milky white fur. After about six months their fur turns black. After 8 to 9 years they are fully mature and their fur reaches its final coloration. Their life expectancy in the wild is about 25 years.

Classification

There are two species of Hoolock:

• Western Hoolock Gibbon, Hoolock hoolock
• Eastern Hoolock Gibbon, Hoolock leuconedys

Western hoolock gibbon

Western Hoolock Gibbon
Conservation status
Endangered (IUCN)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hylobatidae Genus: Hoolock Species: H. hoolock
Binomial name
Hoolock hoolock (Harlan, 1834)

The Western Hoolock Gibbon (Hoolock hoolock) is a primate from the Hylobatidae (gibbon) family. The species is found in Assam, Bangladesh and in Myanmar west of the Chindwin River.

Mootnick and Groves stated that the name Bunopithecus was not valid, and placed it in a new genus, Hoolock. This genus was argued to contain two distinct species which were previously thought to be subspecies: Hoolock hoolock and Hoolock leuconedys.

In India and Bangladesh it is found where there is contiguous canopy, broad-leaved, wet evergreen and semi-evergreen forests. The species is an important seed disperser; its diet includes mostly ripe fruits, with some flowers, leaves and shoots.

There are numerous threats to Western hoolock gibbons in the wild, and are now entirely dependent on human action for their survival. Threats include habitat encroachment by humans, forest clearance for tea cultivation, the practice of jhuming (slash-and-burn cultivation), hunting for food and “medicine”, capture for trade, and forest degradation.

Over the last 30-40 years, western hoolock gibbon numbers are estimated to have dropped from more than 100,000 (Assam alone was estimated to have around 80,000 in the early 1970s) to less than 5,000 individuals (a decline of more than 90%).

Eastern hoolock gibbon

Eastern Hoolock Gibbon
Conservation status
Vulnerable (IUCN)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hylobatidae Genus: Hoolock Species: H. leuconedys
Binomial name
Hoolock leuconedys (Groves, 2005)

The Eastern Hoolock Gibbon (Hoolock leuconedys) is a primate from the Hylobatidae (gibbon) family. The species is found in Myanmar east of the Chindwin River, and in south west Yunnan.

Mootnick and Groves stated that the name Bunopithecus was not valid, and placed it in a new genus, Hoolock. This genus was argued to contain two distinct species which were previously thought to be subspecies: Hoolock hoolock and Hoolock leuconedys.

References

ISBN links support NWE through referral fees

ref name=MSW3>C. Groves, "Order Primates," "Order Monotremata," (and select other orders). Page(s) 178-179 in D. E. Wilson and D. M. Reeder, eds., Mammal Species of the World, 3rd edition, Johns Hopkins University Press (2005). ISBN 0801882214.</ref> Groves, C. (2005-11-16). Wilson, D. E., and Reeder, D. M. (eds). ed. Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. pp. 178-179. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100753. http://www.bucknell.edu/msw3/browse.asp?id=12100753 GENUS Bunopithecus

• Clarke, E., U. H. Reichard, and K. Zuberbühler. 2006. The syntax and meaning of wild gibbon songs. PLoS ONE 1(1): e73. Retrieved January 18, 2007.
• Geissmann, T. 2006a. Hoolock gibbons get a new genus name. Gibbon Journal. Retrieved March 12, 2007.
• Geissmann, T. 2006b. Gibbon systematics and species identification. Gibbons.de. Retrieved April 13, 2006.
• Goodman, M. 1999. The natural history of the primates. American Journal of Human Genetics 64: 31–39.
• Groves, C. P. 1997. Taxonomy and phylogeny of primates. In Molecular Biology and Evolution of Blood Group and MHC Antigens in Primates. Edited by A. Blancher, J. Klein, and W. W. Socha. Berlin: Springer-Verlag. ISBN 3540616365.
• Groves, C. P. 2005. Order Primates, Order Monotremata, (and select other orders). In Mammal Species of the World, 3rd ed. Edited by D. E. Wilson and D. M. Reeder. Johns Hopkins University Press, 178–81. ISBN 0801882214.
• Mootnick, A., and C. P. Groves. 2005. A new generic name for the hoolock gibbon (Hylobatidae). International Journal of Primatology 26: 971–976.
• Napier, J. R., and P. H. Napier. 1985. The Natural History of the Primates. Cambridge, MA: MIT Press. ISBN 026214039X
• Nowak, R. M., and E. P. Walker. 1991. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press. ISBN 080183970X
• Wilson, D. E., and D. Reeder. 1993. Mammal Species of the World: A Taxonomic and Geographic Reference. Washington: Smithsonian Institution Press. ISBN 1560982179.

Primate Info net http://pin.primate.wisc.edu/factsheets/entry/hoolock_gibbon Hoolock gibbon Hoolock Gron KJ. 2008 August 13. Primate Factsheets: Hoolock gibbon (Hoolock) Taxonomy, Morphology, & Ecology. <http://pin.primate.wisc.edu/factsheets/entry/hoolock_gibbon>. Accessed 2009 January 21.

http://www.primate-sg.org/hoolock07.htm Walker, S., Molur, S. and Brockelman, W. Y. 2007. Western Hoolock Gibbon, Hoolock hoolock (Harlan, 1831). In: Primates in Peril: The World’s 25 Most Endangered Primates 2006–2008, R. A. Mittermeier et al. (compilers), pp.18. Unpublished report, IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI), Arlington, VA.

http://www.gibbons.de/main2/08teachtext/facthoolock/hoolockfact.html he Gibbon Network bottom Fact Sheet: Hoolock (Hoolock hoolock) Thomas Geissmann Anthropological Instiute University Zürich-Irchel Winterthurerstrasse 190 CH-8057 Zürich Switzerland E-mail: webmaster@gibbons.de 21 August 2001

External links

• ARKive - images and movies of the hoolock gibbon (Bunopithecus hoolock)
• Hoolock Gibbon photos
• Hoolock Gibbon songs
• Gibbon Conservation Center
• Hoolock Gibbon Photos Taken in The Wild
• Primate Info Net Hoolock Factsheet

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