There are three recognized subspecies:

Saguinus mystax mystax
Spix’s Moustached Tamarin occurs in Peru, south of the Río Amazonas, west to the Ríos Ucayali and Tapiche, south to the junction of the Ríos Urubamba and Ucayali (Hershkovitz 1977; Soini and Soini 1990). Soini and Soini (1990) reported that its Peruvian distribution is more restricted than was indicated by Hershkovitz (1977), occurring only as far west as the east banks of the middle and lower Río Tapiche and lower Río Ucayali. Further south, it extends west again as far as the Río Ucayali, crossing the Río Tapiche at about 6º 40'S. This is based on a specimen from Cerro Azul, Contamana, collected by R. W. Hendee in 1927. Pekka Soini never recorded a moustached tamarin in the basins of the Ríos Pacaya and Samiria despite many years of research there (since 1979), and a specimen from the mouth of the Samiria west of the Río Ucayali (locality 96, Hershkovitz 1977, p.684) collected by H. Bluntschli in 1927 is as such enigmatic. According to Hershkovitz (1979) and the distribution map provided by Aquino and Encarnación (1994), the southernmost limit in Peru is marked by the Ríos Urubamba and Inuya. This is based on the southernmost specimen known for this subspecies from Lagarto on the right bank of the Río Ucayali (Hershkovitz 1977, locality 110, 10º41'S, 73º48'W), collected by the Olalla Brothers in 1928. S. imperator subgrisescens replaces S. m. mystax south of the Ríos Urubamba and Inuya (Hershkovitz 1979). In their text (as opposed to their distribution map), Aquino and Encarnación (1994) give the Río Sheshea, an eastern tributary of the Río Ucayali to the north of the Río Urubamba, as the southern limit, although there is no evidence given for this.

In Brazil, S. m. mystax occurs south of the Rio Solimões, and is largely restricted to the west of the Rio Juruá (Hershkovitz 1977). However, Peres (1990, 1991) recorded S. m. mystax from Jaraqui on the right (east) bank of the lower Rio Juruá. Likewise, Johns (1985, 1986) found that S. m. mystax the Moustached Tamarin occurring on the west bank of the Rio Tefé (east of the lower Río Juruá), with S. m. pileatus replacing it on the east bank. Above the headwaters of the Rio Tefé, the Moustached Tamarin occurring on the right (east) bank of the Rio Juruá is S. m. pileatus, this based on a specimen collected by E. Garbe in 1902, at approximately 7ºS (Hershkovitz 1977).

Saguinus mystax pileatus
According to Hershkovitz (1977), S. m. pileatus occurs south of the Rio Solimões, west of the Rio Purus, south at least as far as the Rio Pauiní or Rio Mamoria. Although Hershkovitz (1977) indicated that it occurs west to the lower Rio Juruá, Johns (1985, 1986) found that the Rio Tefé, its type locality, was its western limit. Judging from a specimen from ‘Juruá (Rio), Amazonas’ (locality 174b, Hershkovitz 1977, p.684), S. m. pileatus extends west to the Rio Juruá above the headwaters of the Rio Tefé. Despite Hershkovitz’s (1977) conviction that S. m. pileatus occurs east as far the Rio Purus on its lower reaches (that is east of the Rio Coarí), we argue that the limited evidence for the distributions of these tamarins suggests that it only reaches the Rio Purus above the Rio Tapauá, with S. m. pluto occurring from the Rio Tapauá, along the left bank of the Rio Purus downriver, and as far west as the Rio Coarí (see the description of the geographic range of S. m. pluto). S. m. pileatus is sympatric with S. fuscicollis avilapiresi throughout its known range.

Saguinus mystax pluto
The distribution of S. m. pluto is rather problematic. Hershkovitz (1968, 1977) argued that it occurs south of the Rio Solimões, between the Rios Purus and Madeira, south to at least 7° or 8° latitude, but the southern limits are not known. The distribution as described by Hershkovitz is based on three localities: 1) The type locality, Lago Ayapuá is on the left (west) bank of the Rio Purus, but Hershkovitz (1977) argued that it must have come from the right bank. 2) Lago do Mapixí, a lake on the right bank of the Rio Purus. Although Hershkovitz states that specimens from Lago do Mapixí are labelled ‘eastern of Rio Purus’ (1977, p.700), this is contradicted in Hershkovitz’s gazeteer (p.933, locality 185, Lago do Mapixí), which states under S. m. pluto ‘C. Lako, June 1931 (left bank of Purus)’. A specimen of S. labiatus, of the same collector with the same date and locality, is ascribed to the right bank of the Purus. (3) Jaburú, on the left bank of the Rio Purus (locality 186, p.933). As in the Ayapuá locality, Hershkovitz (1977) insists that the specimens were in fact taken from the right bank of the Rio Purus and even places the locality on the right bank in the distribution map for S. mystax (p.684, 1977). The problem with accepting that S. m. pluto is known only from the left bank of the Rio Purus is that it would have to be sympatric with S. m. pileatus. Ávila-Pires (1974) placed S. m. pluto to the west of the Rio Purus, and regarded it as a different species for this reason. However, the only specimen of S. m. pileatus recorded for the Rio Purus is São Luis da Mamoria, Rio Purus (locality 188,p.933, Hershkovitz 1977), which is far to the south, near the Rio Pauiní. Although different species, it would be very difficult to accept that S. mystax is sympatric with S. labiatus, because, along with S. imperator, they are evidently ecologically very similar. We suggest that S. m. pluto is in fact restricted to the left bank of the Rio Purus, but is not sympatric with S. m. pileatus, and probably extends east as far as the Rio Coarí and south only to the rio Tapauá. The Mamoria locality for S. m. pileatus is downstream of the mouth of the Rio Pauini and upstream of the mouth of the Rio Tapauá. The Lago do Ipixuna, another locality (183, p.933, Hershkovitz 1977) for S. m. pileatus, is west of the Rio Coarí. There is no evidence of S. m. pileatus occurring east of the Rio Coarí, nor north of the Rio Tapauá.

Izawa and Bejarano (1981) reported two isolated populations of S. mystax from the south of the Rio Acre, north of the Río Tahuamanú, in Bolivia: one between Cobija and Buenos Aires, right bank of the Rio Acre, and another from 10 km north-east of Porvenir, 11°12'S, on the Brazil/Bolivia frontier beyond the headwaters of the Rio Abunã. Izawa and Bejarano (1981) presumed them to be S. m. pluto because Hershkovitz (1977) extended its range south as far as the Abunã headwaters. According to Izawa and Bejarano (1981), these two populations of S. mystax are sympatric with S. labiatus, but do not form mixed species groups as they do independently with S. fuscicollis. There is no ready explanation for these Bolivian populations, more than 3 degrees to the south of the southernmost locality for S. m. pileatus. We consider that they are unlikely to be S. m. pluto, but may be S. m. pileatus (if they cross the upper Rio Purus) or, more likely, a different undescribed subspecies. Izawa and Bejarano (1981) also report a population of S. imperator within the distribution of S. labiatus, along with a new form of S. labiatus (undescribed). It would appear that the distributions of these species are mixed, forming fine-grained mosaics, in the southernmost parts of their ranges, traversing headwaters in a region lacking large rivers as barriers. S. mystax distributions are evidently more complex than portrayed by Hershkovitz (1977) and require further study. Buchanan-Smith et al. (2000) found no evidence for the occurrence of Saguinus mystax in northern Bolivia.

There are three recognized subspecies of mustached tamarins: Saguinus mystax mystax, Saguinus mystax pileatus, and Saguinus mystax pluto. All three subspecies are found in the middle Amazon region of northern Peru and western Brazil.

Biogeographic Regions: neotropical (Native )

Mustached tamarins, being callitrichines, have distinguishing features that set them apart from other New World monkeys. These include their diminutive body size and the presence of claw-like nails on all digits except the hallux. Mustached tamarins have also lost both their upper and lower 3rd molars and the hypocones on their upper molars. The dental formula is 2.1.3.2 / 2.1.3.2. Tamarins have spatulate incisors that are shorter than their canines, unlike marmosets which have incisors and canines of more similar size. The labial and lingual sides of their incisors are also thickened with enamel. Mustached tamarins have jet black pelage on their body and tail and a characteristic white stripe on their upper lip, which gives the appearance of a "white mustache." Mustached tamarins do not have prehensile tails.

Mustached tamarins do not exhibit sexual dimorphism and there are only minor differences in body and canine size between males and females. On average, adult male mustached tamarins weigh 491 ± 23.0 g and measure 61.2 ± 31.2 cm (n=95), whereas adult females weigh 511.0 ± 49.0 g and measure 62.0 ± 29.0 cm (n=80).

According to Cesar and Bicca-Marques (1999), feeding behaviors are correlated with the relative size and shape of hands in callitrichines. Mixed-species groups of tamarins are observed to form only between species that have different foraging behavior, which reduces direct competition. Consequently, due to the specialization conferred by hand morphology, species with dissimilar hand shapes are usually found in association with each other in such mixed-species groups. This is the case in the mixed-species groups of mustached tamarins and saddle-back tamarins. Saguinus mystax captures exposed insects on branches and thus has evolved relatively wide and short hands, as opposed to saddle-back tamarins, which have made use of longer and more slender appendages to manipulate openings in tree trunks and other substrates to search for insect prey.

Range mass: 462 to 560 g.

Average mass: 501 g.

Range length: 30 to 92.4 cm.

Average length: 61.6 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Habitat and Ecology

Systems

• Terrestrial

Mustached tamarins prefer dry, upland forests in the Amazonian lowland and avoid flooded forests.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: rainforest

Being frugivorous-insectivorous, mustached tamarins feed on fruits, flowers, and nectar, insects, and plant exudates. Food sources like gums and soil appear to supplement nutrients and minerals lacking in their main diet of fruits and insects.

Mustached tamarins typically only feed on a small number of plant species in their home range. However, feeding trees are numerous and scattered throughout their home range. Feeding trees are usually continuously fruiting and produce a small amount of fruits daily, hence mustached tamarins may visit the same trees regularly over a span of several months to exploit the resources.

In a group of mustached tamarins in northeastern Peru, up to a third of feeding time was spent feeding on nectar from Symphonia globulifera in the dry season. Mustached tamarins concentrated their foraging efforts on trees that yielded more nectar, despite having to travel greater distances between feeding sessions in some cases. Therefore, proximity of feeding trees from one another did not predict foraging patterns, as mustached tamarins preferentially chose feeding trees that allowed them to feed for longer periods of time instead of trees that were closer and would thus minimize traveling time from one tree to another.

Although feeding trees are typically scattered throughout their home range, mustached tamarins are able to remember the locations of the important feeding trees to minimize efforts in foraging. The use of spatial memory and learning in foraging are important because they provide "an efficient means of exploiting a widely scattered set of predictable feeding sites" (Garber, 1989, p. 212).

Gum feeding is highly seasonal, but it is a major dietary staple during dry and early wet seasons when other food sources are scarce. Furthermore, gum exudates balance mineral intake, which will otherwise suffer from the effects of a low-calcium and high-phosphorus insectivorous diet.

Since mustached tamarins lack the dental specialization to gouge holes into tree bark, gum feeding is "dependent principally on either natural weathering of the bark or on the parasitic activity of woodboring insects, or both" (Garber, 1992, p. 471).

Heymann and Smith (1999) found that Saguinus mystax concentrated gum feeding in the afternoon. They hypothesized that this may be "a behavioral strategy to prolong the time that the gums are retained in the gastrointestinal tract" (p. 468). Prolonged passage allows for better digestion and more complete microbial fermentation of the substrates. This in turn yields nutritional benefits while providing these small animals with a means to generate heat during the night via the fermentation process.

Garber (1992) described mustached tamarins as exhibiting "a highly opportunistic foraging pattern," with "seasonal exudate feeding, occasional trunk foraging patterns, and small-branch fruit and insect feeding" (p. 471).

The main vertebrate prey for mustached tamarins includes "katydids (Tettigoniidae, Orthoptera), stick grasshoppers (Proscopiidae, Orthoptera), and spiders (Araneidae), although lizards (Squamata) and frogs (Anura) were also taken" (Smith, 2000, p. 315). Mustached tamarins also feed on nestling birds, albeit less frequently. They forage for prey at higher levels within the forest strata than Saguinus fuscicollis (average of 8.84 m vs. 1.50 m; Smith 2000), and also capture most prey from slender and horizontal substrates.

Animal Foods: birds; amphibians; reptiles; insects

Plant Foods: fruit; nectar; flowers; sap or other plant fluids

Primary Diet: omnivore

Mustached tamarins play an important ecological role in their habitat by dispersing seeds of plant species in primary and secondary rain forest, and thus indirectly impact forest regeneration and maintenance.

As mustached tamarins are opportunistic feeders and are able to explore many kinds of plant resources, they are able to disperse a great variety of seed species.

Due to their small size, there is a limit to the size of seeds that they can disperse. Seasonal changes in diet, sleeping and resting patterns, and variation in foraging behavior and migration may also affect their contribution to seed dispersal in the rainforest.

On a negative note, mustached tamarins have been observed to be highly destructive in their nectar-feeding activities but the widespread ecological impact of this has not been demonstrated.

Mustached tamarins that foraged near human settlements were found to have higher prevalence of a primate parasite, Prosthenorchis elegans. However, in the same study by Wentz et al. (2010), mustached tamarins were not found to be infected by human parasites even though they lived in close proximity to human communities with high rates of infestation of nematodes such as Ascaris lumbricoides and hookworms.

Ecosystem Impact: disperses seeds

Mutualist Species:

• Saguinus fuscicollis

Commensal/Parasitic Species:

• Prosthenorchis elegans

Due to their small size, mustached tamarins are vulnerable to predation by a large number of terrestrial predators, such as tayras (Eira barbara), ocelots (Leopardus pardalis), and jaguarundis (Puma yagouaroundi). Large snakes like Boa constrictor and birds of prey are also important predators.

Cooperative defense against predators was observed in a tribe of mustached tamarins in northeastern Peru. Members of this tribe successfully rescued a mustached tamarin that was being attacked by a Boa constrictor by counter-attacking the predator. The tribe subsequently avoided low heights for a week after the attack, as further deterrence to attacks by snakes.

In general, mustached tamarins counter predators by avoiding attracting attention. Mustached tamarins are camouflaged in densely foliated areas and they carefully select resting and sleeping sites that have lower chances of being exposed. They may also choose resting sites that are physically isolated from surrounding vegetation, as this would increase the likelihood of them being able to detect approaching predators.

Known Predators:

• tayras (Eira barbara)
• ocelots (Leopardus pardalis)
• jaguarundis (Puma yagouaroundi)
• boa constrictors (Boa constrictor)

Anti-predator Adaptations: aposematic ; cryptic

Allogrooming and scent marking have been studied in S. mystax societies. Allogrooming or social grooming is commonly observed in mustached tamarins, but it is not practiced equally by all members of a troop. In one study by Heymann (1996), an adult male contributed 70% of all grooming observed in a group, without bias to any one of the other members in his troop. The reasons for this asymmetry are not well-characterized but may be attributed to differences in social standing or competition for reproductive success. As mentioned above, breeding females may employ social grooming as a way of encouraging other members in her troop to stay to assist in parental care duties.

The use of scent marking for territorial demarcation is variable among Saguinus species. In both wild and captive S. mystax, there is little evidence for the use of scent marking in territorial defense.

Scent marking functions prominently in intra-group communication and female mustached tamarins are more likely to engage in scent marking behavior, compared to males. On the contrary, male mustached tamarins are more likely to respond to scent marks of the opposite sex, which may be related to mate selection. Mustached tamarins do not engage in "collective scent marking" or allomarking, unlike in S. fuscicollis.

The rates of scent marking by mustached tamarins are directly proportional to the duration of occupation of areas by the troop. Intense scent marking in more frequented areas enhances the effectiveness of olfactory communication between members of the same troop.

Vocalization has also been demonstrated to be a form of communication in S. mystax, such as in situations where a mustached tamarin becomes separated from its troop. According to Snowdon and Hodun (1985, p. 211), "The long-call structure of the moustached tamarin is similar to that of its sympatric tamarin species, saddleback tamarins. In both species the calls last 2 to 3 seconds, consist of several short, frequency-modulated syllables, and has a frequency range of 8 to 12 kHz". The same study also noted that "nonbreeding adult females gave fewer calls" and they were also slower to make the first long call upon separation. This could reflect "the relatively low status of nonreproductive mature females" (p. 211) in their troop, which is usually centered on a single breeding female. Members of a troop are able to recognize members of their troops by responding to long calls from separated members. This ability to distinguish individual members suggests that a S. mystax troop in the wild is able to maintain its integrity by ensuring that all members are accounted for.

Early morning vocalizations and subsequent coordinated movement patterns within mixed-species troops of mustached tamarins and saddle-back tamarins are also crucial in maintaining group integrity on a daily basis.

Communication Channels: visual ; tactile ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; acoustic

There are inconclusive data on the longest lifespan of mustached tamarins in the wild, though individuals in captivity have been known to live in excess of 20 years.

Typical lifespan

Status: captivity: >20 (high) years.

Maximum longevity: 20 years (captivity)

Mustached tamarins usually associate in stable troops, which vary widely in size. For example, the mean group size was found to be 6 to 7 individuals per group in two studies (Garber et al., 1993; Löttker et al., 2004), with a range of 4 to 11 individuals in each group.

The reproductive strategy of S. mystax is described as polyandrous or polygynous. Each group is typically centered on one breeding female, which is usually also the oldest female. Despite the lack of breeding opportunities, adult non-breeding females may continue to persist in the group, and may ascend to breeding female status in the event of death or illness of the current breeding female.

A study by Löttker et al (2007) suggests that breeding females use social grooming as incentive to induce adult males and non-breeding offspring to stay in the group as helpers to care for their young.

Adult mustached tamarins live in highly tolerant and cooperative societies. Garber (1997) estimated that the frequency of cooperative to aggressive acts between adult mustached tamarins was 52:1. Intragroup sexual aggression between male mustached tamarins is exceedingly rare, but mate guarding may be practiced by the dominant breeding adult male during the breeding female’s most fertile periods.

Male mustached tamarins may compete for reproductive success via sperm competition and other physiological mechanisms. For example, testes volume in males within a group varied greatly among individuals and this could directly impact reproductive viability of males.

Despite a polyandrous mating system and seemingly a lack of evidence of strong competition or aggression over breeding opportunities, a genetic analysis of paternity in mustached tamarins revealed that 67 to 100% of S. mystax infants in a troop were fathered by the same adult male. Genetic relatedness within a troop is high but both non-related and related adults can co-exist in a troop. There is a need for a better understanding of the critical factors that govern the observed reproductive bias among adult S. mystax males.

Mating System: polyandrous ; polygynous ; polygynandrous (promiscuous) ; cooperative breeder

Mustached tamarins have characteristic twinned births, with an annual birth peak from November through March. Some S. mystax troops experience 2 birthing cycles, from June to October and in February and March.

Spatio-genetic analysis of a population of mustached tamarins in Peru by Huck et al. (2007) revealed variable genetic relatedness within a troop. Migration is common among male and female mustached tamarins, but females are often required to travel for longer distances than males before settling down with a new troop due to scarce breeding opportunities in a polyandrous mating society. Matings are generally between non-closely related partners, hence the degree of inbreeding is reduced.

Breeding interval: Mustached tamarin breeding intervals are not reported.

Breeding season: There is an annual birth peak from November through March. Some S. mystax troops experience 2 birthing cycles, from June to October and in February and March.

Average number of offspring: 2.

Average gestation period: 145 days.

Average birth mass: 46.9 g.

Average weaning age: 171 days.

Average age at sexual or reproductive maturity (female): 486 days.

Average age at sexual or reproductive maturity (male): 540 days.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous

Average birth mass: 46.9 g.

Average gestation period: 145 days.

Average number of offspring: 2.

Average age at sexual or reproductive maturity (male)

Sex: male: 540 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 486 days.

Maternal infanticide, while rare, has been documented twice in Saguinus species, in S. mystax by Culot et al. (2011) and S. fuscicollis by Herrera et al. (2000). In both cases, infanticides occurred under circumstances of low availability of helpers (2 to 3 male helpers compared to 4 to 5 helpers at other times) and presence of more than 1 breeding female in the troop. Both of these factors lower the likelihood of obtaining sufficient care for the infant within the group.

The single most important determinant of maternal infanticide could be the mother’s perception of low probability of survival of her infant in the group, which is directly caused by external factors in the troops, such as low helper availability. Low helper availability or competition for care with infants from another breeding female in the same troop greatly reduces the chances of survival for infant mustached tamarins. Maternal infanticide may thus represent a strategy to maximize efforts that go into ensuring survival of infants. On the contrary, infanticide of unrelated infant tamarins by male mustached tamarins, which is usually attributed to sexual selection pressures, has never been observed in Saguinus. Males do not gain reproductive advantages from infanticide, as infant mortality has minimum effect on the mother’s fertility status. Female mustached tamarins remain reproductively viable during nursing of their young.

Due to the cooperative breeding behavior of S. mystax, the number of helpers available in a group to care for the young has a strong influence on the survival of infant tamarins (Garber, 1997).

Birth intervals were also shorter during the periods when infanticide occurred (1 to 2.5 months). In Saguinus fuscicollis, which also practices cooperative breeding like S. mystax, the optimal birth spacing is 3 months, so as to allow for efficient care of the young. Shorter birth intervals increase the burden on the troop to care for the young, and this effectively reduces the likelihood of providing adequate care for all of them.

Although not demonstrated in S. mystax, care and transport of infants results in significant personal costs for small-sized mustached tamarins. Loss of body mass of carriers of infants has been demonstrated in wild and captive Saguinus oedipus. Cooperative breeding allows the costs of caring for the young to be distributed to other members of a troop to a certain extent, and carriage of infant mustached tamarins is not restricted to certain members of a troop, as members usually take turns in transporting the young when foraging.

Parental Investment: precocial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents

Mustached tamarins are on the least concern list of animals on The IUCN Red List of Threatened Species (last assessed in 2008). Populations of wild mustached tamarins have been noted to be stable, although habitat destruction remains a threat to species living in the Amazonian rainforest.

The effects of agriculture on S. mystax populations in Peru have been studied. Populations recovered and even exceeded pre-agricultural numbers due to "increased reproductive rate, early breeding, and reduced infant mortality", while "immigration seemed to play a minor role" (Ramirez, 1984, p. 258).

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: least concern

Population

Population Trend

Major Threats

Conservation Actions

Although commensally associated with human communities, there is no evidence for adverse economic effects on humans.

Saguinus mystax, like other tamarin species, has been used extensively in biomedical research, e.g., in the development of the hepatitis A vaccine.

Positive Impacts: research and education