New data on the ecology and geographic distribution of Saguinus inustus Schwarz , 1951 ( Primates , Callitrichidae

Saguinus inustus (Schwarz, 1951) is one of the neotropical primates least studied. The distribution of the species ranges from the north of the Solimões River, between the Negro and Japurá Rivers in Brazil, and Guayabero-Guaviare Rivers in Colombia. Nevertheless, due to the low number of specimens collected from the lower Japurá and lower Negro Rivers areas, the geographic distribution is so far poorly delineated. In this study, field data was composed of sightings and the collection of specimens during a survey of mammal diversity in the Amana Sustainable Development Reserve (ASDR). For this survey, two 40-day expeditions were carried out in 2004. The first one occurred during the flooded season in June and July, and the second was during the peak of the dry season in October. Direct sightings were made through hiking along transects, navigation along water channels with a 30-hp speedboat, and gliding along flooded trails in the forest. New records of S. inustus were made in 11 different localities in ASDR. The study has confirmed the presence of the species in the Amanã area, carrying out the first records of the species in flooded forest habitats.


Introduction
Saguinus inustus (Schwarz, 1951) is one of the least studied Neotropical primates.According to the literature, the species has been found in only 16 sites (Hershkovitz, 1977;Hernández-Camacho and Defler, 1993;Barnett et al., 2002;Defler, 1983Defler, , 2004;;Iwanaga, 2004;Palácios et al., 2004;Souza, et al. 2004) and only 16 individuals have been deposited in scientific collections.The distribution of the species ranges from the north of the Solimões Rivers, between the Negro and Japurá Rivers in Brazil, and Guayabero-Guaviare Rivers in Colombia (Hershkovitz, 1977; Hernández-Camacho and Defler, 1993;Defler, 2004;Souza et al., 2004).Nevertheless, due to the low number of specimens collected from the lower Japurá and lower Negro Rivers areas, the geographic distribution is so far poorly delineated.
In 1980, Rylands (unpubl., reported in Barnett et al., 2002) carried out the first record of the species in the Amanã Sustainable Development Reserve (ASDR) area, sighting a group of S. inustus along the north margin of Amanã lake.Iwanaga (2004) confirmed through local reports the presence of the species in two localities of the Jaú National Park: the "Janela Monteiro" site and the "Janela Floresta", both along the Jaú River.Souza et al. (2004) collected a male adult killed by local residents of the Boa Esperança community, located at Amanã lake (02° 28'12" S and 64° 44' 27'' W), and deposited it at Mamirauá Institute's collection (IDSMasto-001).Souza et al. (2004) also observed groups of the species in terra-firme forest, close to the community area.Souza et al.'s observations were made at the opposite margin of that of the recordings carried out by Rylands (Barnett et al., 2002).
All sightings of S. inustus described in literature were made in terra-firme forest (Defler, 1983; Hernández-Camacho and Defler, 1983;Barnett et al., 2002;Iwanaga, 2004;Souza et al., 2004).The aim of this study is to update the information on the geographic distribution and use of habitat by S. inustus, reporting new occurrences and sightings in habitats different from those recorded in literature.

Methods
Secondary data was obtained through literature review (Hershkovitz, 1977;Hernández-Camacho and Defler, 1991;Barnett et al., 2002;Defler, 1983;2004;Iwanaga, 2004;Palácios et al., 2004;Souza et al., 2004) and records of Brazilian scientific collections (IDSM and MPEG).Field data was composed by sightings and collection of specimens during a survey of mammal diversity in the ASDR (IBAMA nº.086/2004 -CGFAU/LIC).For this survey, two 40-day expeditions were carried out in 2004.The first one occurred during the flooded season in June and July, and the second was during the peak of the dry season in October.Direct sightings were made through hiking along transects, navigation along water channels with a 30-hp speedboat, and gliding along flooded trails in the forest.
Two monitoring trails were opened: the Ubim trail located on the left margin of Ubim creek at the left bank of Amanã lake (02° 30' 37" S and 64° 36' 40" W), and the Bacaba trail on the right margin of Amanã lake (2° 30' 37" S and 64° 36' 40" W).Using line transect sampling methods (Emmons, 1984;Buckland et al., 1993) observations were made about group size and habitat use.Stomach and bowel contents of specimens collected were deposited in the Mamirauá Institute scientific collection, whereas furs, skulls and skeletons were deposited in the MPEG.Two individuals were later donated to IDSM.Tissues for DNA extraction were deposited in the Universidade Federal do Pará, Molecular Biology Laboratory.
Not much difference was observed between male and female sizes collected in ASDR (Table 2).Females were 4.5% taller and 2.5% heavier than males.Only two males were collected and their weight and length did not differ from those collected by Souza et.al. (2004) (TL 670 g, n = 1).
Four groups were sighted on monitoring trails, three in terra firme forest and one in igapó forest, on the right margin of Amanã lake (Table 3).These groups were composed of two, three, and four individuals (2.75 average, n = 4, sd = 0.96).Due to the small number of sightings on monitoring trails, it was not possible to estimate abundance of the species in the area.Nevertheless, it seems that groups sighted at Amanã were smaller from those sighted in the Caquetá Rivers region, in Colombia.In that area, Palacios et al. ( 2004) sighted groups that varied from three to eleven individuals (06 average, n = 5, sd = 2.7), and Defler (2004) reported the existence of groups with three, seven and eight individuals.
Two out of four groups sighted were in association with double-toothed kites (Harpagus bidentatus).Although local people affirmed that these birds follow S. inustus to predate them, field sightings suggested foraging associations.This avian species is predominantly insectivorous, but may also feed from small vertebrates (Fontaine 1980;Boinski and Scott, 1988).Previous records show that insectivorous birds may benefit from association with primates, capturing prey trying to escape from predation.This behaviour helps them catch previously inaccessible prey, raising foraging efficiency and protection against other predators (Boinski and  1 for information on each of the records.Scott, 1988;Egler, 1991).This type of association has been observed in other species of Saguinus (Egler, 1991;Haymann, 1992) and other genus of primates (Greenlaw, 1967;Fontaine 1980;Boinski and Scott, 1988;Marsh, 2004;Hankerson, 2006).
Saguinus inustus is categorised as least concern in the IUCN red list (2009), but in Amanã the species is relatively abundant, often sighted around manioc gardens and in transects for biodiversity monitoring.No hunting event was recorded for the species, and local people af-firm that S. inustus is not hunted for subsistence due to one of its characteristics -its low weight.The species is, nevertheless, used as a pet, and in some rare cases it is commercialised, as observed by Souza et. al. (2004).

Conclusions
Although this study has almost doubled the number of records of S. inustus, much more data is needed to better understand its geographical distribution.The study has confirmed the presence of the species in the Amanã   1).The assumption that it occurs along all lower Japurá-Negro interfluve remains to be confirmed.The correct delimitation of its range is of fundamental importance for its conservation.Further studies are urgently needed to assess the status of S. inustus, besides longterm research on its ecology and behaviour.

Figure 1 .
Figure 1.Geographical distribution of the Saguinus inustus specimens.See Table1for information on each of the records.

Table 1 .
Update of records of Saguinus inustus.

Table 2 .
General characteristics of specimens collected in Amanã Sustainable Development Reserve.Fur donated to the Mamirauá Institute collection. *

Table 3 .
Groups of S. inustus sighted in monitoring transects.out the first records of the species in flooded forest habitats.The expected geographic distribution of the species covers 23,464,000 ha, 61% of which are protected, either in indigenous land or protected areas (Figure