Dryas Monkey
Encyclopedia
The Dryas monkey also known as Salonga monkey or ntolu, is a little-known species of guenon
found only in the Congo Basin
, restricted to the left bank of the Congo River
. It is now established that the animals previously classified as Cercopithecus salongo (common name Zaire Diana monkey) were in fact Dryas monkeys. Some older sources treat the Dryas monkey as a subspecies of the Diana monkey
and classify it as Cercopithecus diana dryas, but it is geographically isolated from any known Diana monkey population.
While the Dryas monkey formerly was considered data deficient
, recent evidence suggests it is very rare and its total population possibly number less than 200 individuals. Consequently, its status was changed to critically endangered
in the 2008 IUCN Red List.
Its preferred habitat is believed to be secondary forest
or the upper story of primeval forest. Dryas monkeys feed mainly on plant materials, primarily fruit, flowers, and young leaves, though they will also take some invertebrate
s.
So far it is known that the Dryas monkey is a fairly typical forest guenon. Body size varies from 40 to 55 cm, with a tail an additional 50–75 cm. Adults weigh between 4 and 7 kg, with marked sexual dimorphism
. Its markings are similar to those of the Diana monkey, except that its lower back and forelimbs are greenish-grey in colour.
Group sizes range up to 30 individuals, with only a single adult male. The gestation period is 5 months, with normally a single infant being born. Sexual maturity is reached after 3 years. In captivity, a lifespan of up to 19 years has been recorded.
Guenon
The guenons are the genus Cercopithecus of Old World monkeys. Not all the members of this genus have the word "guenon" in their common names, and because of changes in scientific classification, some monkeys in other genera may have common names that do include the word "guenon"...
found only in the Congo Basin
Congo Basin
The Congo Basin is the sedimentary basin that is the drainage of the Congo River of west equatorial Africa. The basin begins in the highlands of the East African Rift system with input from the Chambeshi River, the Uele and Ubangi Rivers in the upper reaches and the Lualaba River draining wetlands...
, restricted to the left bank of the Congo River
Congo River
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...
. It is now established that the animals previously classified as Cercopithecus salongo (common name Zaire Diana monkey) were in fact Dryas monkeys. Some older sources treat the Dryas monkey as a subspecies of the Diana monkey
Diana Monkey
The Diana monkey is an Old World monkey found in West Africa, from Sierra Leone to Côte d'Ivoire.The Diana monkey ranges from 40 to 55 cm in length, excluding its tail, which is of a uniform 3–4 cm diameter and 50–75 cm long. Adults weigh between 4–7 kg...
and classify it as Cercopithecus diana dryas, but it is geographically isolated from any known Diana monkey population.
While the Dryas monkey formerly was considered data deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
, recent evidence suggests it is very rare and its total population possibly number less than 200 individuals. Consequently, its status was changed to critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
in the 2008 IUCN Red List.
Its preferred habitat is believed to be secondary forest
Secondary forest
A secondary forest is a forest or woodland area which has re-grown after a major disturbance such as fire, insect infestation, timber harvest or windthrow, until a long enough period has passed so that the effects of the disturbance are no longer evident...
or the upper story of primeval forest. Dryas monkeys feed mainly on plant materials, primarily fruit, flowers, and young leaves, though they will also take some invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s.
So far it is known that the Dryas monkey is a fairly typical forest guenon. Body size varies from 40 to 55 cm, with a tail an additional 50–75 cm. Adults weigh between 4 and 7 kg, with marked sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
. Its markings are similar to those of the Diana monkey, except that its lower back and forelimbs are greenish-grey in colour.
Group sizes range up to 30 individuals, with only a single adult male. The gestation period is 5 months, with normally a single infant being born. Sexual maturity is reached after 3 years. In captivity, a lifespan of up to 19 years has been recorded.