Plecturocebus olallae 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Primates Pitheciidae

Scientific Name: Plecturocebus olallae Lönnberg, 1939
Common Name(s):
English Olalla Brothers’ Titi, Beni Titi Monkey, Olalla's Titi, Olalla’s Titi Monkey, Ollala Brothers' Titi
Spanish Lucachi rojizo, Mono Tití
Callicebus olallae Lönnberg, 1939
Taxonomic Source(s): Byrne, H., Rylands, A. B., Carneiro, J. C., Lynch-Alfaro, J. W., Bertuol, F., Da Silva, M. N. F., Messias, M., Groves, C. P., Mittermeier, R. A., Farias, I., Hrbek, T., Schneider, H., Sampaio, I. and J. P. Boubli. 2016. Phylogenetic relationships of the New World titi monkeys (Callicebus): first appraisal of taxonomy based on molecular evidence. Frontiers in Zoology 13(10).
Taxonomic Notes: Kobayashi and Langguth (1999) and van Roosmalen et al. (2002) recognize five species groups – cupreus, donacophilus, moloch, personatus and torquatus. van Roosmalen et al. (2002) place Callicebus olallae in the donacophilus group, along with: Callicebus donacophilus, Callicebus pallescens, Callicebus oenanthe and Callicebus modestus. Tarifa (1996), Anderson (1997) and Felton et al. (2006) suggest that the taxonomic distinctiveness between C. olallae and Callicebus modestus requires further investigation. However, more recent field observations (Martinez and Wallace 2007) and opportunistically collected specimens (R. Wallace pers. comm.) support the taxonomic separation of C. olallae and C. modestus. Preliminary results from a scat-based genetic study show that both are clearly distinct from C. donacophilus, and from each other (Barreta pers. comm. to R. Wallace).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(ii,iii,v) ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Veiga, L.M., Wallace, R.B. & Martinez, J.
Reviewer(s): Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
This species is listed as Endangered because of its extremely restricted range (400 km²) in a region subject to ongoing forest loss, fragmentation and hunting pressure, all of which are likely to increase with the improvement of a regional highway. The species does not occur in any protected areas.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to Bolivia with very restricted range estimated to be 400 km² (Martinez and Wallace 2007). Recent surveys have revealed that C. olallae is apparently confined to gallery forest and adjacent forest islands of the Yacuma River, with just one other locality in gallery forest of the Manique River (Martinez and Wallace 2007), both in south-western Beni Department. In contrast to the geographic distribution proposed by van Roosmalen et al. (2002), Felton et al. (2006) argue that the species only occurs to the east of the Río Beni. Extensive surveys in the region have since confirmed this to be the case (Martinez and Wallace 2007). The geographical range of Callicebus olallae overlaps with Callicebus modestus, although transitional zones between the two taxa have yet to be confirmed and each seems to specialize on different habitat types (Felton et al. 2006; Martinez and Wallace 2007). Found below 400 m a.s.l.
Countries occurrence:
Bolivia, Plurinational States of
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The species was formerly only known from the type locality (La Laguna, 5 km from Santa Rosa, [upper río] Beni, Bolivia, altitude about 200 m; Patterson 1992, Tarifa 1996; Anderson 1997). In 2002, Felton et al. (2006) conducted titi monkey surveys and interviewed local residents at four locations: Puerto Santa Cruz on the Río Yacuma; the type locality of La Laguna; Petaca; and Naranjal. Titis were relatively abundant in Naranjal, not encountered in Petaca (although local residents claim they occur there), and are no longer present in La Laguna (probably exterminated through hunting). Examination of holotypes indicates that groups encountered in Rio Yacuma were C. olallae, while two of three groups found in Naranjal were Callicebus modestus (the third appeared to combine characters from both species).

Lopez-Strauss (2007) estimated density for both C. olallae and C. modestuss using calling behavior and an adapted point-count methodology. C. olallae presented conservative density estimates of between 1.8 and 11.5 groups per km² (Lopez-Strauss 2007).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:This taxon occurs in relatively dry forest patches within a forest-savanna mosaic, apparently restricted to gallery forest and immediately adjacent forest islands (Lonnberg 1939; Anderson 1997; Felton et al. 2006; Martinez and Wallace 2007).

Titis are frugivores, monogamous primates that generally live in small family groups. Three groups, each with two members, were encountered at Puerto Santa Cruz, to the north of the Rio Yacuma. Aggressive displays were directed towards the researchers. Martinez and Wallace (2007) and Lopez-Strauss (2007) details average group sizes of 2.7 and 2 individuals respectively.

Threats [top]

Major Threat(s): There is some forest loss and habitat fragmentation within its range. Groups surveyed by Felton et al. (2006) occurred in fragments surrounded by cattle ranches. A farmer in Naranjal reported seeing groups crossing grassland gaps (300–400 m) between patches of forest (Felton et al. 2006) and this behaviour has since been confirmed (J. Martinez and Lopez pers. comm.). Uncontrolled grassland fires are also a major threat especially if they jump to forest patches (J. Martinez pers. comm.). Critically, the proposed major improvement to a regional road will exacerbate deforestation and is likely to increase hunting pressure (Felton et al. 2006).

The disappearance of the species from the type locality - La Laguna - indicates that they may be threatened locally by hunting (Felton et al. 2006). They are used as bait for fishing and cat hunting and some are captured for pets. Apparently the presence of sympatric primates such as Saimiri may also be a threat to C. olallae (J. Martinez pers. comm.).

Conservation Actions [top]

Conservation Actions: The species does not occur in any protected areas. It is listed on CITES Appendix II.

Conservation programmes in the region include: the Greater Madidi Landscape Conservation Program in northern La Paz and south-western Beni Departments and Kaa-Iya Landscape Conservation Program in Santa Cruz Department of the Wildlife Conservation Society and the Asociación Boliviana para la Conservación and Conservation International in the south-western Beni Department.

Citation: Veiga, L.M., Wallace, R.B. & Martinez, J. 2008. Plecturocebus olallae. The IUCN Red List of Threatened Species 2008: e.T3554A9939925. . Downloaded on 21 September 2018.
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