Piliocolobus oustaleti (Trouessart, 1906)

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 : 710-711

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Oustalet’s Red Colobus

Piliocolobus oustaleti

French: Colobe d'Oustalet / German: Oustalet-Stummelaffe / Spanish: Colobo rojo del Ubangui

Other common names: Ubangi Red Colobus

Taxonomy. Colobus oustaleti Trouessart, 1906 ,

Youmba, right bank of lower Oubangui (= Ubangi), 0° 18’ N, 17° 30’ E.

Modern taxonomic arrangements of the colobus monkeys either divide the red colobus and the Olive Colobus into two genera, Piliocolobus and Procolobus , respectively, or consider them to belong to one genus, Procolobus , with two subgenera ( Procolobus for the Olive Colobus and Pil-1ocolobus for the red colobus). We follow here C. P. Grovesin his publications of 2001 and 2007 in using two genera. The southwestern most locality, Pombo (1° 13° 127 S, 16° 9° 36” E), is very close to Butando where P. bouvieri is found, but there is no indication of intermediates between them. Monotypic.

Distribution. Extreme S South Sudan, S Central African Republic, N DR Congo (N to Sili, Uele District, 4° 2° 24” N, 27° 6’ 36” E, Dedegwa, Garamba, 4° 20° N, 29° 25’ 48” E, S to the Congo River, and E to Lake Albert), NE Republic of the Congo (N to Mongoumba, 3° 23’ N, 18° 21'E, and Bakota, S bank of the Lobaye River, 3° 22" 43” N, 17° 20° 24” E, and SW to Pombo, Sangha Department).

Descriptive notes. Head-body 45.9-68 cm (males) and 52-64 cm (females), tail 55-5— 73 cm (males) and 68-73 cm (females); weight 12-5 kg (males) and 8-2 kg (females). Oustalet’s Red Colobus is a large, robust, sexually dimorphic species, with a short tail. It is dark speckled smoky-brown (sometimes brownish-fawn) above, and slightly paler below (buffy to whitish or pale red). The crown does not, or hardly, contrasts with back. The whiskers are grayish. Hands and feet are dark to black. This is another very variable Central African species. Some individuals in the Ubangi/Lobaye area are described as “raw sienna brown,” underparts may be golden, and tail root has a coppery red patch. Those from the Uele River (north-eastern DR Congo) gallery forest region tend to be lighter brownish-fawn, with forelimbs and lower legs especially pale, contrasting with dark hands and feet. Finally, there is a deep red-colored morph both in the south-western part of the distribution and in the extreme east, on the borders of the Ituri Forest, the latter probably due to gene-flow from the hybrid swarm described under the Semliki Red Colobus ( P semlikiensis ). In both mtDNA and vocalizations, Oustalet’s Red Colobus groups with other species of red colobus in East Central Africa. Nevertheless, like other species of red colobus in the Congo Basin, Oustalet’s Red Colobus carries at least two very divergent lineages of mtDNA, with different specimens from different sites clustering with other red colobus species instead of with one another. A prominent tuft of hair (“panache”) is present, although it is shorter than on the Tshuapa Red Colobus ( P. tholloni ). Like Foa’s Red Colobus ( P. foai ), Oustalet’s Red Colobus has small teeth. Cranially, Oustalet’s Red Colobus , Foa’s Red Colobus , the Semliki Red Colobus , and the Ashy Red Colobus ( P. tephrosceles ) form a group—all have a long palate, early closing skull sutures, and angular orbits.

Habitat. Mature primary lowland, tropical moist forest, swamp and gallery forest, and savanna woodland. In the Ngotto Forest of the Central African Republic, however, Oustalet’s Red Colobus only occurs in flooded forests on alluvial riverbanks.

Food and Feeding. Diets include young leaves and mature leaves, fruit, flowers, buds, and possibly seeds. One study reported that groups regularly entered water to collect bulbs of aquatic plants.

Breeding. There is no information available for this species.

Activity patterns. Oustalet’s Red Colobusis diurnal and arboreal.

Movements, Home range and Social organization. Group sizes of Oustalet’s Red Colobus were 3-18 individuals at one site. Groups there spent 30% of their time in the lower forest canopy, less than 10 m above the ground.

Status and Conservation. CITES Appendix II. Classified as Least Concern on The IUCN Red List (as Procolobus rufomitratus oustaleti ). Oustalet’s Red Colobus is likely to be among the more numerous of the red colobus taxa, given its very wide distribution north of the Congo River where there are still large areas of forest and low human densities. Nevertheless, it is heavily hunted for the bushmeat trade. It occurs in Okapi Wildlife Reserve and Tayna Gorilla Reserve in DR Congo and Nouabalé-Ndoki National Park in the Republic of the Congo. It is also found in Ngotto Classified Forest and the proposed Mbaéré-Bodingué National Park in the Central African Republic.

Bibliography. Brugiere et al. (2005), Galat-Luong & Galat (1979b), Gautier-Hion & Brugiére (2005), Gautier-Hion et al. (1999), Groves (2001, 2007b), Grubb et al. (2003), Moreau et al. (1946).

Figures

Distribution. Extreme S South Sudan, S Central African Republic, N DR Congo (N to Sili, Uele District, 4° 2° 24” N, 27° 6’ 36” E, Dedegwa, Garamba, 4° 20° N, 29° 25’ 48” E, S to the Congo River, and E to Lake Albert), NE Republic of the Congo (N to Mongoumba, 3° 23’ N, 18° 21'E, and Bakota, S bank of the Lobaye River, 3° 22" 43” N, 17° 20° 24” E, and SW to Pombo, Sangha Department).