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Primates
Id code: amd305Cercopithecidae
Cercopithecus dryas
Schwartz, 1932
(Eng) Dryas guenon
(Fre) Cercopithèque dryas
Taxonomic notes
The species includes C. salongo, definitively recognised as an age-variant of this species (Colyn et al. 1991; Oates, 1996).
IUCN threat category
Data Deficient (DD).
Available information
Very little is known on the ecology and distribution of this guenon. Some notes on the habitat are given by Thys Van Der Audenaerde (1977), who refers to a specimen initially classified as a new species (Cercopithecus salongo), but later attributed to the species C. dryas (Colyn et al., 1991). The ecology of the species is briefly described in Colyn (1987) and Kuroda et al. (1985). A distribution map is included in Colyn (1988) and Lernould (1988). General information on the species’ ecology is found in Gautier-Hion et al. (1988), Kingdon (1997) and Stuart & Stuart (1997). Status and distribution are discussed in Oates (1996).
Known extent of occurrence
C. dryas is known only from a few localities in central former Zaire. The precise boundaries of its range are still imprecise because of its secretive habits. The distribution map (Fig. 2.3.9.a) was derived from Kingdon (1997).
Categorical-discrete (CD) distribution model
The species’ preferred habitat type is thought to be secondary forest (Kingdon, 1997; Lee et al., 1988).
Based on these environmental preferences, the following scores were assigned (Fig. 2.3.9.b) (Tab. 2.3.9.a):
|
Score |
|
|
1 |
Secondary rainforest. |
|
2 |
Other forest types and forest mosaics. |
|
3(*) |
Savannas and croplands. |
|
(*) Scores increased for vegetation types occurring inside a 1-km buffer around permanent water |
|
|
suitable |
moderately suitable |
unsuitable |
Total |
||||
|
km2 |
% |
km2 |
% |
km2 |
% |
km2 |
% |
|
21 256 |
14 |
122 126 |
82 |
6 129 |
4 |
149 511 |
100 |
Tab 2.3.9.a: Cumulative size (km2) of areas pertaining to each environmental suitability class within the Extent of Occurrence.
|
Number Patches (NP) |
Mean Patch Size (MPS) km2 |
Patch Size SD (PSSD) km2 |
Largest Patch Index (LPI) % |
Mean Shape Index (MSI) |
Area-Weighted Mean Shape Index (AWMSI) |
|
|
suitable |
92 |
229 |
1 527 |
10.26 |
1.26 |
6.13 |
|
moderately suitable |
21 |
5 842 |
25 230 |
82.54 |
1.62 |
7.45 |
|
Total AO |
1 |
143 750 |
0 |
100 |
4.33 |
4.33 |
Tab 2.3.9.b: Area of Occupancy fragmentation indexes.
Probabilistic-continuous (PC) distribution model
The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.9.c.
Validation
No occurrence of the species within the four sample areas.
Comments and conservation issues
The known EO is based more on hypothesis than good data and very little can be inferred from the available data. From what we currently know, the EO appears to be sufficiently suitable and non fragmented. However, the models can be of little help when the available data are so poor. Probably the whole EO should be marked as "possible" until the true status of the species is verified. The species is correctly classified as Data Deficient. About 10% of the total AO is included in the existing protected areas (basically the Salonga National Park).
|
SUITABILITY CLASS |
inside |
outside |
Total |
|
suitable |
0.68 |
13.54 |
14.22 |
|
moderately suitable |
8.98 |
72.70 |
81.68 |
|
unsuitable |
0.84 |
3.26 |
4.10 |
|
Total |
10.50 |
89.50 |
100 |
Tab 2.3.9.c: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.
References
Colyn M.M. (1987). Les primates de la foret ombrophile de la Cuvette du Zaire: interprétations zoogéographique des modèles de distribution. Rev. Zool. Africaine: 101, 183-196.
Colyn M.M. (1988). Distribution of guenons in the Zaire-Lualaba-Lomani River system. In: Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York: pp 104-124.
Colyn M.M., Gautier-Hion A., Thys Van Der Audenaerde D.F.E. (1991). Cercopithecus dryas Schwarz 1932 and C. salongo Thys Van Der Audenaerde 1977 are the same species with an age-related coat pattern. Folia Primatologica: 56, 167-170.
Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds) (1988). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York.
Kingdon J. (1997). The Kingdon field guide to African Mammals. Academic Press, London and New York: Natural World.
Kuroda S., Kano T., Muhindo K. (1985). Further information on the new monkey species Cercopithecus salongo Thys van den Audenaerde, 1977. Primates: 26(3), 325-333.
Lee P.C., Thornback J., Bennet E.L. (1988). Threatened Primates of Africa. IUCN, Gland - Switzerland and Cambridge, UK.
Lernould J. (1988). Classification and geographical distribution of guenons: a review. In: Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York: pp 54-78.
Oates J.F. (1996). African Primates Status Survey and Conservation Action plan. IUCN/SSC Primate Specialist Group.
Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers.
Thys Van Der Audenaerde D.F.E. (1977). Description of a monkey-skin from East-Central Zaire as a probably new monkey-species (Mammalia, Cercopithecoidae). Rev. Zool. Africaine: 91, 1000-1010.