Pithecia pithecia

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 : 475

32.

White-faced Saki

Pithecia pithecia

French: Saki a téte pale / German: Weilskopfsaki / Spanish: Saki de cara blanca

Other common names: Guianan Saki, Pale-headed Saki; Golden-faced/Golden-headed Saki (chrysocephala), Guiana White-faced Saki (pithecia)

Taxonomy. Simia Pithecia Linnaeus, 1766 ,

Guiania (= La Guyane or French Guiana).

In his 1987 review of the genus, P. Hershkovitz concluded that the type specimen was probably collected in the vicinity of the city of Cayenne, French Guiana. The taxonomy of Pithecia followed here is that proposed by Hershkovitz in 1987. A taxonomic revision currently being undertaken by L. K. Marsh will provide a broader and more accurate understanding of the diversity and distributions of the sakis. Populations between the rios Nhamunda and Trombetas resemble a mix of both P. p. chrysocephala and P. p. pithecia , and boundaries of both subspecies’ distributions are unclear further north in Amapa, Roraima, and Para and need further investigation. Two subspecies recognized.

Subspecies and Distribution.

P.p.pitheciaLinnaeus,1766—GuianaShieldforestsinEVenezuela(SoftheOrinocoandEofthelowerRioCaroniinthestatesofDeltaAmacuroandBolivar),theGuianas,andNBrazil(EoftheriosNegroandBranco,andintheS—neartheRioAmazonas,E,andNEoftheRioTrombetasinthestatesofRoraima,Amazonas,Para,andAmapa);theiroccurrencefurtherWandSinVenezuelaandintheParqueNacionalCanaimaisunknown.

P. p. chrysocephala 1. Geoffroy Saint-Hilaire, 1850 — Brazil, N of the Rio Amazonas-Solimoes, both sides of the lower Rio Negro, E to Faro and the Rio Nhamunda. Amazonian Brazil, N of Rio Amazonas, both sides of the Rio Negro S to near Manacapuru, E to Faro along the Rio Nhamunda.

Descriptive notes. Head-body 33-39.5 cm (males) and 32.3-41.5 cm (females), tail 39.8-45.5 cm (males) and 37-43.5 cm (females); weight 1-4—1-7 kg (males) and 1-4 kg (females) for the “Guiana White-faced Saki ” (P. p. pithecia ). Head—body 28.5-46 cm (males) and 30.2-33.3 cm (females), tail 34—45 cm (males) and 32.8-40 cm (females); weight 1-9 kg (males, n = 2) and 1-9 kg (females, n = 5) for the “Golden-faced Saki ” (Pp. chrysocephala). While all species of sakis are dichromatic to varying degrees, the White-faced Saki is one of the most striking in the genus. In both subspecies, females have grayish, mottled pelage with bright orange chests. The Golden-faced Saki also has black facial hair, bright orange malar lines, and a white star on its forehead. Males of both subspecies are predominantly black without streaking in full adults, and they have distinct white (Guiana white-faced Saki ) or orange-reddish (Golden-faced Saki ) complete facial disks. In both subspecies, juvenile males are transitional in appearance and more closely resemble females through their subadult stage.

Habitat. Mature forest that includes variations of flooded forest, swamp ( Mauritia palm swamps for some), terra firma forest, and seasonally flooded forests (varzea and igapo). White-faced Sakis can be found in disturbed habitats and fragments with secondary forest. Nevertheless, as seed predators of large forest tree species (e.g. Lecythidaceae ) they tend to reach higher densities in mature forest. The saki’s ability to occupy a wide range of forest typesis related to their very large geographic distributions.

Food and Feeding. Sakis are seed predators and folivores, but they also eat fruits, leaves, fungi, and insects. They have a specialized dentition with long canines (average 2:5 mm), allowing them to break open unripe and tough fruits to eat seeds and nuts. In a 12month study conducted on Lago Guri, one of the only long-term study sites for White-faced Sakis, M. Norconk and N. Conklin-Brittain found that they ate foods high in lipids, such as young seeds and arils of plants. These foods accounted for a high monthly lipid intake compared with a relatively low intake of crude protein and simple sugars. They suggested that sakis allow their diets to be high in fibrous and astringent foods as a trade-off for those that are also lipid rich. Studies in Venezuela indicated that diets were strongly dominated by seeds (61%), followed by fleshy fruits (28%), leaves (7%), flowers (2%), and insects (2%). Principal plant families in the diet were Connaraceae , Lecythidaceae , LLoganiaceae, Fabaceae , and Erythroxylaceae .

Breeding. The White-faced Saki tends to have a single offspring. As many as three females in a group can be cycling or pregnant at the same time. Five interbirth intervals after weaning were 12-36 months. Although researchers often assume sakis are monogamous, multiple breeding female White-faced Sakis can coexist in groups without evidence of reproductive suppression. Births peak in November—April (dry season) in Venezuela and October—January (dry season and short wet season) in Suriname.

Activity patterns. White-faced Sakis are diurnal and arboreal. They move through the mid-canopy quadrupedally and may often leap between vertical trunks in a vertical clinging and leaping mode of locomotion. This is unique among sakis because those living further west in the upper Amazon Basin tend to only run quadrupedally in the upper forest canopy.

Movements, Home range and Social organization. Although the characteristic group size and typical mating system of wild sakis are still uncertain, free-ranging groups of White-faced Sakis have 2-12 individuals, with 2-3 adult females and 1-4 adult males. In larger groups, more than one female breed, but it is not known if supernumerary males are a result of delayed dispersal or whether there are two or more males in groups that are reproductively active. Home ranges of 10-15 ha have been recorded, with daily movements of 1500-1830 m.

Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List, including both subspecies. The White-faced Saki is wide ranging and adaptable. It occurs in numerous protected areas, some of them very large.

Bibliography. Cunningham & Janson (2007), Gilbert & Setz (2001), Gregory & Norconk (2006), Hershkovitz (1979b, 1987a), Homburg (1997), Kinzey & Norconk (1993), Kinzey et al. (1988), Lehman et al. (2001), Mittermeier (1977), Norconk (1996, 2006, 2011), Norconk & Conklin-Brittain (2004), Norconk & Setz (2013), Norconk, Grafton & McGraw (2013), Norconk, Raghanti et al. (2003), Oliveira et al. (1985), Rylands & Mittermeier (2008), Setz & Gaspar (1997), Setz et al. (1999), Thompson & Norconk (2013).

Figures

On following pages: 20. Madidi Titi (Callicebus aureipalatii); 21. Medem'’s Titi (Callicebus medemi); 22. White-collared Titi (Callicebus torquatus); 23. White-chested Titi (Callicebus lugens); 24. Yellow-handed Titi (Callicebus lucifen; 25. Rio Purus Titi (Callicebus purinus); 26. Rio Jurué Collared Titi (Callicebus regulus); 27. Black-fronted Titi (Callicebus nigrifrons); 28. Masked Titi (Callicebus personatus); 29. Southern Bahian Titi (Callicebus melanochir); 30. Blond Titi (Callicebus barbarabrownae); 31. Coimbra-Filho's Titi (Callicebus coimbral).

Subspecies and Distribution. P.p.pitheciaLinnaeus,1766—GuianaShieldforestsinEVenezuela(SoftheOrinocoandEofthelowerRioCaroniinthestatesofDeltaAmacuroandBolivar),theGuianas,andNBrazil(EoftheriosNegroandBranco,andintheS—neartheRioAmazonas,E,andNEoftheRioTrombetasinthestatesofRoraima,Amazonas,Para,andAmapa);theiroccurrencefurtherWandSinVenezuelaandintheParqueNacionalCanaimaisunknown. P. p. chrysocephala 1. Geoffroy Saint-Hilaire, 1850 — Brazil, N of the Rio Amazonas-Solimoes, both sides of the lower Rio Negro, E to Faro and the Rio Nhamunda. Amazonian Brazil, N of Rio Amazonas, both sides of the Rio Negro S to near Manacapuru, E to Faro along the Rio Nhamunda.