Aceramarca opossums (Gracilinanus aceramarcae) are found in the Andes Mountains of north and central South America, in southeastern Peru and northwestern Bolivia. These animals have been trapped near the Aceramarca River and in the Unduavi Valley, near La Paz, Bolivia. (Creighton and Gardner, 2008; Patterson and Solari, 2008; Voss, et al., 2009)
Aceramarca opossums are found in montane rainforests in the Andes Mountains. They are also found in mossy cloud, bamboo and elfin forests, as well as sphagnum bogs and pajonales at elevations ranging from 2,530 to 3,350 meters. This species has been documented near streams in the Unduavi Valley and near the Aceramarca River. (Creighton and Gardner, 2008; Patterson and Solari, 2008; Voss, et al., 2009)
Aceramarca opossums are small, pouchless marsupials with long, reddish-brown dorsal pelage and grayish-orange ventral pelage. Their gray snout is very narrow and they have a buff colored chin. These animals are adapted for an arboreal lifestyle, as evidenced by their extremely long tail. Their total body length is about 245 mm, including a tail length of about 142 mm and hind feet that are about 16 mm long. In general, Aceramarca opossums have a tail-to-body ratio of 1.5. On average, this species weighs about 23 grams. Aceramarca opossums are occasionally mistaken for their relatives, agile (Gracilinanus agilis) and wood-sprite opossums (Gracilinanus dryas); however, Aceramarca opossums have longer fur with more prominent guard hairs and smaller molars than the other species. Other members of genus Gracilinanus are sexually dimorphic, where males are larger than females; however, it is not known whether this applies to Aceramarca opossums as well. Members of the genus Gracilinanus may grow lifelong, these species are short-lived; however, the rare individuals that survive multiple years tend to be noticeably larger. In general, the temperature and metabolic rate of didelphids tends to be lower than similarly sized placental mammals. (Creighton and Gardner, 2008; Diaz, et al., 2002; Pires, et al., 2010; Voss, et al., 2009)
Didelphids engage in a polygynous mating system. There is very little information specific to Aceramarca opossums; however, the extreme competition among males for breeding females may cause a massive amount of stress. Other members of genus Gracilinanus are considered partially semelparous because many of the males die shortly after breeding. This trend is considered only partial because a few males do survive to a second or even third breeding season. (Cooper, et al., 2009; Fernandes, et al., 2010; Martins, et al., 2006a)
There is very little information specifically regarding the reproductive behavior of Aceramarca opossums. Much more research has been conducted on their close relative, Brazilian gracile opossums. It is not known whether these species share all reproductive traits, however, it is not unlikely that these species share at least some reproductive traits. Brazilian gracile opossums begin mating when they are about 1 year old. This species reproduces seasonally; females are receptive during the end of the cool dry season, from August to September. Several pregnant and lactating females have been captured in September to December. Brazilian gracile opossums’ strategy of synchronous estrous means that their young are born in October to December, during the first half of the warm wet season when insect prey are most populous. This likely optimizes the female’s ability to capture food while caring for young. Litters are composed of 6 to 14 individuals, with an average of 11 offspring. Weaning begins at about 2 to 3 months of age, when the young weigh about 8 to 10 grams. (Martins, et al., 2006b; Martins, et al., 2006a; Pires, et al., 2010)
Genus Gracilinanus is composed of pouchless marsupials. Both attached and unattached young usually stay near their mother; however, older offspring may stay behind in the nest while their mother forages. Brazilian gracile opossum, a close relative of Aceramarca opossums, wean their offspring when they are about 2 to 3 months old, during the warm wet season. (Hershkovitz, 1992; Martins, et al., 2006a; Pires, et al., 2010)
There is currently no information regarding the lifespan of Aceramarca opossums specifically, however, other members of genus Gracilinanus typically live 1 to 2 years. Likewise, other members of this genus are considered partially semelparous; most males do not survive to a second breeding season. Among Brazilian gracile opossums, a close relative of Aceramarca opossums, males invest so much in competing for mates that they often show fur loss, poor body condition and are more likely to become infested with parasites after the beginning of the breeding season. Although females also have a short lifespan, they survive to a second year more frequently than males. In general, offspring from the preceding season replace the adults each year. (Cooper, et al., 2009; Martins, et al., 2006b; Martins, et al., 2006a; Pires, et al., 2010)
Members of genus Gracilinanus are solitary and nocturnal; they typically only come together for breeding. While member of this genus may forage in a similar location, they do not interact. These animals are mostly arboreal, but may forage on the ground. Other members of this genus are known to enter torpor when the temperature is colder than 20°C. (Cooper, et al., 2009; Hershkovitz, 1992; Pires, et al., 2010)
There is currently no information regarding the home range size of Aceramarca opossums. However, their close relative, Brazilian gracile opossums have home range sizes of approximately 1,400 meters squared for males and 1,200 meters squared for females. (Fernandes, et al., 2010; Pires, et al., 2010)
There is very little information regarding the communication or perception of genus Gracilinanus. Members of this genus may produce a variety of sounds defensively or when they are startled, these sounds include hissing, growling and screeching. It has been suggested that arboreal marsupials are more vocal and have more adept vision than their non-arboreal counterparts; however, no conclusive studies have been conducted. (Bradshaw, et al., 1998; Delciellos and Vinicius, 2009; Hershkovitz, 1992)
Very little is known about the feeding habits of Aceramarca opossums. Other members of genus Gracilinanus are primarily insectivorous, consuming mostly beetles, ants and wasps. In addition, other members of the genus also eat fruits, especially during the dry season and are important seed dispersers. Although these species are arboreal, most forage on the ground. (Cooper, et al., 2009; Creighton and Gardner, 2008; Hershkovitz, 1992; Martins and Bonato, 2004; Martins, et al., 2006b; Martins, et al., 2006a; Pires, et al., 2010; de Carmargo, et al., 2011)
There is currently no information regarding the predation of Aceramarca opossums specifically, however, general predators of genus Gracilinanus may include various owls, snakes and lizards. Similar species are predated upon by white-tailed hawks, crab-eating foxes, oncillas, maned wolves, margays and jaguarundis. Likewise, the remains of unidentified members of genus Gracilinanus have also been recorded in the scat of ocelots, coatis and striped owls. (Bianchi and Mendes, 2007; Bianchi, et al., 2011; Ferreira, et al., 2013; Granzinolli and Motta-Junior, 2006; Hershkovitz, 1992; Motta-Junior, et al., 2004; Pires, et al., 2010)
Aceramarca opossums are likely insectivores and seed dispersers. There is currently no specific information regarding parasitism of the species, however, other members of genus Gracilinanus are known to be hosts of a variety of nematodes, lice and botfly larvae. (Cooper, et al., 2009; Creighton and Gardner, 2008; Cruz, et al., 2009; Feijo, et al., 2008; Martins and Bonato, 2004; Martins, et al., 2006b; Martins, et al., 2006a; Pires, et al., 2010; Puttker, et al., 2008; Torres, et al., 2007; Torres, et al., 2009; de Carmargo, et al., 2011)
Positive impacts of Aceramarca opossums on human populations are currently not known.
Negative impacts of Aceramarca opossums on human populations are currently not known.
Aceramarca opossums are currently listed as a species of least concern according to the IUCN Red List of threatened species. Although this species is rarely seen and has not been studied thoroughly, it is believed that they have a large population size. Likewise, much of their habitat is found in protected areas. (Patterson and Solari, 2008)
Leila Siciliano Martina (author), Animal Diversity Web Staff.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
having more than one female as a mate at one time
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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