Cercopithecus dryas, Schwarz, 1932

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 550-755 : 679

59.

Dryas Monkey

Cercopithecus dryas

French: Cercopitheque dryas / German: Dryas-Meerkatze / Spanish: Cercopiteco dryas

Other common names: Dryad Monkey, Ekele, Lomela Monkey, Salongo Monkey, Wamba Monkey

Taxonomy. Cercopithecus dryas Schwarz, 1932 ,

Congo-Zaire, Sankuru District, Lomela.

The original description of C. dryas was based on a photograph of a pet, 2-year old juvenile male and its incomplete skin and skull in Lomela (2° 20° S, 23° 12’ E), a town on the Lomela River that marks the north-eastern boundary of Salonga National Park. The origin of this pet is unknown, but H. Schouteden argued, in 1946, that it may have been taken from Watsi, a village on the right bank of the Tshuape River, but the locality was never confirmed. In 1977, D. F. E. T. Van den Audenaerde described an adult guenon (believed to be male), from Wamba in the Zone de Djolu (¢.250-260 km north of Lomela), as C. salongo . In 1991, M. Colyn, J.-P. Gautier, and Van den Audenaerde concluded that C. salongo is in fact an adult C. dryas , but E. Sarmiento, in 2002, argued that C. dryas and C. salongo may well, in fact, be distinct species and that further research was needed. In his note, Sarmiento indicated that, following the suggestion of Schouteden, there is a town called Watsi Kengo in the northern sector of Salonga National Park (c.1° 00’ S, 20° 38’ E) where it might have come from. Watsi Kengo is a 1-2day walk south from the fork of the Lomela and Tshuapa rivers, and there is a logic that the pet in the town of Lomela (upriver on the Lomela River) could have come from there. Djolu, near Wamba (0° 01" N-0° 01" S, 22°31’-33" E), is the type locality of C. salongo . It is to the north of Watsi Kengo, south and west of the Lopori River. In his 1966 monograph, W. C. O. Hill concluded it was a subspecies of C. diana , and Thys van den Audenaerde in his description of C. salongo also suggested a close relationship with C. diana . The likeness is superficial, however, and aspects of their ecology and cranial morphology argue against it. The speciesis quite distinct, possibly a sister to all other Cercopithecus species, and with C. salongo as a junior synonym, C. P. Groves assigned C. dryas to its own species group, the dryas species group; this arrangement is followed here. Sarmiento did not discount the possibility that salongo may be a subspecies of C. dryas . Monotypic.

Distribution. Congo Basin in DR Congo (Equateur Province) in the Kokolopori Bonobo Reserve; it is unknown to people N of the Lopori. Its distribution is otherwise a mystery, but it is supposed it would extend between the Lopori River and the Luo River to the W;its possible occurrence in the Lolema River Basin to the S has not been confirmed.

Descriptive notes. Head-body 35-38 cm, tail 50 cm (females; no information for males); weight 3 kg (males) and 2-3 kg (females). The Dryas Monkey is one of the smallest guenons. Back and upper limbs are grayish chestnut. It has a creamy-white or white chin, and cheek-whiskers and a white brow, framing a triangular black face. White side whiskers are separated from the white brow band on either side by a thin posterio-superiorly directed bare, line of black facial skin. There are elongated tufts between crown and temples. Chest, inside upper arms and legs, and abdomen, extending to buttocks, are white. Adults have jet black lower limbs, both inside and out. A white patch on buttocks and posterior thighs extends along tail. Dark color on tail is restricted to a thin line along its upper surface and a black tip. The male hasslightly longer white fur on the chin than the female. Scrotum is light blue. In juveniles, black on limbs and tail is absent, and there is very little white on buttocks.

Habitat. Mixed mature and secondary forest, but also tropical, riparian, and swamp forest to ¢.380 m above sea level. Four small populations of Dryas Monkeys have been identified in mixed mature and young second growth forest in the Kokolopori Bonobo Reserve.

Food and Feeding. Dryas Monkeys feed mainly on fruits, supplemented with young leaves and shoots from plants such as Aframomum (Zingiberaceae) and Megaphrynium (Marantaceae) .

Breeding. There is no information available for this species.

Activity patterns. Dryas Monkeys are diurnal and semi-terrestrial, generally using lower levels of the forest canopy. At Wamba, they are almost always reported on or close to the ground. They often forage on the ground. Locomotion is quadrupedal.

Movements, Home range and Social organization. Dryas Monkeys are reported to live in multimale-multifemale groups of up to 30 individuals, but usually 2-15 individuals. They form mixed groups with other guenons such as Wolf’s Monkey (C. wolft) and the Red-tailed Monkey ( C. ascanius ) that occur in the same region. Little is known of Dryas Monkeys in their natural habitat.

Status and Conservation. CITES Appendix II. Classified as Critically Endangered on The IUCN Red List. The Dryas Monkey is listed as Class B in the African Convention on the Conservation of Nature and Natural Resources. Its known distribution is tiny, and itis clear from survey work that its numbers are low, probably not exceeding a few hundred individuals. All currently known individuals are present in the region along the left bank of the lower Lopori River, possibly restricted in the west by the Luo River. They are known to occur in just one protected area, Kokolopori Bonobo Reserve of 50,000 ha. There has been no recent information concerning their existence to the south in the Lomela River Basin. Reports to date have indicated that Dryas Monkeys occur near but not in Salonga National Park, but no surveys have been carried out specifically to address the possibility ofits occurrence in, for example, the northern sector. They are hunted for food. Conservation measures centered on the Dryas Monkey in the Kokolopori Bonobo Reserve are being carried out by the non-governmental organizations, Vie Sauvage and the Bonobo Conservation Initiative.

Bibliography. Aimquist et al. (2010), Colyn (1988), Colyn, Gautier-Hion & Thys van den Audenaerde (1991), Gautier-Hion & Brugiere (2005), Gautier-Hion et al. (1999), Groves (2001, 2005b), Goodwin (2011a), Grubb et al. (2003), Hart, Butynski & Hurley (2008), Hill (1966), Kingdon (1997), Kuroda et al. (1985), Lokasola & Hurley (2007), Oates (1996b), Sarmiento (1999/2000), Thys Van den Audenaerde (1977).

Figures

59. Dryas Monkey (Cercopithecus dryas), 60. Diana Monkey (Cercopithecus diana), 61. Roloway Monkey (Cercopithecus roloway), 62. De Brazza’s Monkey (Cercopithecus neglectus), 63. Mona Monkey (Cercopithecus mona), 64. Campbell's Monkey (Cercopithecus campbelli), 65. Lowe's Monkey (Cercopithecus lowei), 66. Crowned Monkey (Cercopithecus pogonias), 67. Wolf's Monkey (Cercopithecus wolf), 68. Dent's Monkey (Cercopithecus dent)

Distribution. Congo Basin in DR Congo (Equateur Province) in the Kokolopori Bonobo Reserve; it is unknown to people N of the Lopori. Its distribution is otherwise a mystery, but it is supposed it would extend between the Lopori River and the Luo River to the W;its possible occurrence in the Lolema River Basin to the S has not been confirmed.