Callicebus modestus, Lonnberg, 1939

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Phitheciidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 432-483 : 459

1.

Rio Beni Titi

Callicebus modestus

French: Titi du Rio Beni / German: Rio-Beni-Springaffe / Spanish: Titi del Beni

Other common names: Beni Titi Monkey, Bolivian Titi, Modest Titi, Rio Beni Titi

Taxonomy. Callicebus modestus L önnberg, 1939 ,

El Consuelo, Rio Beni, Bolivia.

C. modestus is considered to be cranially primitive and C. P. Groves in 2001 and 2005 placed it in the modestus species group. S. Kobayashi and M. van Roosmalen placed it in the C. donacophilus species group. There may be some overlap with the distribution of C. olallae , although the two species appear to occur in distinct habitats. Monotypic.

Distribution. N Bolivia (Beni Department); distribution is poorly known, but it appears to be restricted to the Rio Beni Basin, E of the Beni and W to the Rio Manique.

Descriptive notes. Head-body 31-5 cm (males), tail 40 cm (males); weight ¢.800 g. The Rio Beni Titi is similar in size to othertitis in the donacophilus species group. Its body is predominantly light brownish or reddish agouti, with a reddish brown agouti forehead and crown, and a thin blackish superciliary fringe. Hands and feet are blackish or blackish mixed with reddish. Tail is blackish agouti, slightly darker than body. Ear tufts are distinctly white or off-white, and sideburns are the same color as forehead and crown.

Habitat. Patches of relatively dry forest in a forest-savanna mosaic at elevations of up to 400 m. In the fragmented habitats found in their present landscape, Rio Beni Titis are known to cross gaps of 300-400 m on the ground.

Food and Feeding. There is no information available for this species.

Breeding. There is no specific information available for this species, but all titis form monogamous breeding pairs. The male provides parental care by carrying the single offspring.

Activity patterns. There is no information available for this species.

Movements, Home range and Social organization. Mean group sizes of Rio Beni Titis at two sites were 2-6 and three individuals. At one othersite, however, two large groups of five and seven individuals were observed. The smaller group contained three adults, whereas the larger one had six adults and an infant, which is a highly unusual composition for a titi group, normally only a single adult pair. The larger groups were probably the result of a temporary aggregation of individuals unable to disperse adequately in a highly fragmented landscape. Density estimates of the Rio Beni Titi are up to 12-4 groups/km?, which suggests a home range size of c.10 ha, although much lower densities (as low as 0-9 groups/km?*) have been recorded at some sites.

Status and Conservation. CITES Appendix II. Classified as Endangered on The [UCN Red List. The main threat to the Rio Beni Titi is deforestation and habitat fragmentation in its relatively small geographic distribution, estimated at 1800 km*. Some hunting for pets has also been observed. The Rio Beni Titi occurs in part of the Beni Biological Station Biosphere Reserve, but otherwise, populations are unprotected.

Bibliography. Anderson (1997), Felton et al. (2006), Hershkovitz (1988, 1990), Loépez-Strauss (2008), Martinez & Wallace (2007, 2010), Norconk (2011), Rowe & Martinez (2003), Salazar-Bravo et al. (2003), Tarifa (1996), Veiga, Wallace & Martinez (2008a).

Figures

On following pages: 4. Olallas’ Titi (Callicebus olallae); 5. San Martin Titi (Callicebus oenanthe); 6. Coppery Titi (Callicebus cupreus); 7. Red-crowned Titi (Callicebus discolon; 8. Ornate Titi (Callicebus ornatus); 9. Chestnut-bellied Titi (Callicebus caligatus); 10. Doubtful Titi (Callicebus dubius); 11. Stephen Nash's Titi (Callicebus stephennashi); 12. Caqueta Titi (Callicebus caquetensis);, 13. Ashy Titi (Callicebus cinerascens); 14. Hoffmanns's Titi (Callicebus hoffmannsi); 15. Lake Baptista Titi (Callicebus baptista); 16. Red-bellied Titi (Callicebus moloch).

Distribution. N Bolivia (Beni Department); distribution is poorly known, but it appears to be restricted to the Rio Beni Basin, E of the Beni and W to the Rio Manique.