Lestoros inca

Geographic Range

Incan shrew opossums ( Lestoros inca ) are found in the Andes Mountains in Peru and Bolivia. They have been found near the headwaters of Rio Alto Madre de Dios, Rio Marcapata, and Rio Inamberi, as well as in departmento Las Paz, Bolivia.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

It has been suggested that this species prefers environments that are somewhat less wet than the other members of family Caenolestidae . However, they have been trapped in a variety of wet mossy areas, as well as drier scrub environments. Incan shrew opossums are found in montane environments with low trees, bushes and grasses, often in cloud or elfin forests. They have been found in elevations ranging from 1,800 to 3,600 meters.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• mountains mountains

Physical Description

Incan shrew opossums are marsupials. They are somewhat shrew-like in appearance and have elongated faces. They are the only members of the genus Lestoros , but are very similar in appearance to genus Caenolestes ; however, Incan shrew opossums have smaller upper canines. Incan shrew opossums have thick, medium length, dark gray fur. They have curved ears, small eyes and long hind feet. These animals have whiskers on their chin, side of their nose and their forelimbs. Their total body length is approximately 90 to 120 mm, including a tail length of 105 to 135 mm, approximately the same length as their body. Incan shrew opossums weigh between 20 to 35 grams.

In general, members of family Caenolestidae can be distinguished from other marsupial groups by their unique dentition. They have a reduced number of incisors and their lower middle incisors are large and have a forward slope. The dental formula for genus Caenolestes is: I 4/3, C 1/1, P 3/3, M 4/4, 46 teeth total. While their tail is not prehensile, it is used for support while they climb and for balance. Shrew opossums have short robust limbs, each containing 5 digits; their middle 3 digits are shorter than the outside two. Their humeri are extremely heavy; their femurs are relatively slender in comparison. Members of family Caenolestidae have unusual lip flaps, which may function as a method of preventing debris from interfering with their whiskers or it may help prevent ingestion of unwanted debris. Similar to other marsupials, Caenolestid females have 2 uteri and 2 vaginas. Members of genus Caenolestes lack a pouch but do have 4 mammae, 2 on either side of their abdomen. Caenolestids are sexually dimorphic, with adult males larger than adult females.

Common shrew opossums ( Caenolestes obscurus ), another member of family Caenolestidae , show evidence of a low metabolic rate, based on their body temperature (35.4° C), their body weight (about 40 g), their cool habitat and their thick fur coat. This species shows no evidence of entering torpor.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

There is currently little information available regarding the mating system of Incan shrew opossums.

Female Incan shrew opossums lack a marsupium; however, immature individuals may have an undeveloped fold of skin that they lose before reaching maturity. Females have 4 mammae available for their young to nurse. Evidence suggests that Caenolestid females have the same number of ova as mammae, unlike family Didelphidae . In support of that notion, a female was found pregnant with 3 embryos, 2 in the right uterus and 1 in the left. These animals likely have one annual breeding season from February to August.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

No information is currently available regarding this species.

Lifespan/Longevity

There is currently no information on the longevity of Incan shrew opossums.

Behavior

Members of genus Caenolestes are solitary; they are primarily active during the early evening and at night. They are terrestrial, but they are also adept climbers. During the day, these animals stay in tunnels under tree roots. When they are active, they travel through paths in dense vegetation.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• solitary solitary

Home Range

There is currently no information available about the home range of Incan shrew opossums.

Communication and Perception

Members of family Caenolestidae have very small eyes and poor eyesight. Incan shrew opossums have tactile whiskers on their chin, the side of their nose and their forelimbs. Their unusual lip flaps have the hypothesized function of clearing debris from their sensitive vibrissae, but they may merely function as a method of preventing the ingestion of unwanted debris. Their somewhat primitive brains have enlarged olfactory bulbs, which could indicate an enhanced sense of smell. When they are startled they attempt to hide and they hiss when cornered. Caenolestids are not noted for frequent production of sound, however, captive individuals may make several sounds including whistles, bird-like screams, rat-like squeaks and drawing air through their incisors.

• Communication Channels
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Members of genus Caenolestes are opportunistic feeders. Their stomach contents indicate that they are primarily insectivores. Ingested invertebrates include beetles , crickets , butterfly larvae, centipedes , grasshoppers , spiders , and earthworms . A smaller proportion of their diet is composed of vegetation, fruit and small vertebrates including juvenile mice . They forage for food in moss and leaf litter. When they find a food item, they manipulate and consume it with their forepaws, from a semi-seated position. As Caenolestids shear their food with their incisors, they produce a clicking sound.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• mammals
• insects
• terrestrial non-insect arthropods
• terrestrial worms

• Plant Foods
• leaves
• fruit

Predation

There is currently little information regarding the predation of Incan shrew opossums. However, there are several carnivores known to inhabit a similar range and prey upon small mammals , such predators include Andean Mountain cats ( Leopardus jacobita ), pampas cats ( Leopardus colocolo ), culpeo foxes ( Lycalopex culpaeus ) and cougars ( puma concolor ), among others.

Ecosystem Roles

Incan shrew opossums have an insectivorous diet. Likewise, Caenolestids are often plagued by lice of the genus Cummingsia . Interestingly, Australian marsupials are also affected by similar lice , related to the family level. Incan shrew opossums are known to carry chiggers ( Sasacarus incae ), mites ( Xenomyobia hirsute , Hoffmannina peruensis , and Crotiscus brennani ) and nematodes ( Pterygodermatites hymanae ). Caenolestids may also become infested with South American hard ticks ( Ixodes jonesae ).

Economic Importance for Humans: Positive

Due to their human-inaccessible habitat, there has been very little study of these animals. Likewise, there has been very little interaction between human and shrew opossum populations. They may, however, serve as a control of insect populations.

Economic Importance for Humans: Negative

There are no known negative effects of Incan shrew opossums on human populations.

Conservation Status

Incan shrew opossums are currently plentiful in protected areas and are listed as a species of least concern on the IUCN Red List of threatened species.

Additional Links

Encyclopedia of Life

Contributors

Leila Siciliano Martina (author), Texas State University.

References

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