Philander deltae

Geographic Range

Philander deltae , the Orinoco four-eyed opossum, is found only in the Río Orinoco delta of northeastern Venezuela. This includes the Gulf of Paria and the alluvial plains of the Orinoco, Morichal Largo, Guanipa, and San Juan rivers.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Philander deltae live in evergreen forests with trees 15-25 m in height that are permanently or seasonally flooded by the Río Orinoco.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

• Wetlands
• marsh marsh
• swamp swamp

• Other Habitat Features
• riparian riparian

Physical Description

Like all species of the genus Philander , this species has lighter spots above the eyes, giving the appearance of “four eyes.” It also has a slim body and a relatively large head with a long, conical-shaped muzzle. All species in this genus also have slim, partially furred prehensile tails that are equal to or longer than the body length. Individuals have opposable pollex on the forefeet and opposable hallux on the hindfeet. Females have fully developed pouches.

Philander deltae is a relatively small species for the genus Philander , with a total body and tail length of 475-550 mm. Its fur is short and velvety with a brownish dorsum and cream-colored venter. A darker brown band runs dorsally from the head to the base of the tail. Gray-based fur intrudes into the cream color between the fore and hind limbs. The face is dark brown and cheeks are cream-colored. The spots above the eyes are relatively small, as are the spots just behind the ears. Their ears are relatively small, naked, and pigmented black along the edges. The tail is furred up to 20% from the base and pigmented 75% from the base. The tail comprises about 50% of the total length of P. deltae .

Although P. deltae appears similar to other South American Philander species, its distribution does not overlap with any other Philander species. However, the very small supraorbital spots, few light hairs behind the ears, small ears, and tail with pigmented skin 75% or more from the base all distinguish P. deltae from other Philander species.

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

Reproduction

Little is known about the reproductive behavior of P. deltae , but this species was once classified under Philander opossum , which has been studied more extensively. Philander opossum has a year-round breeding season, but successful reproduction depends on food availability, so young are found mostly in the wet season. Females can have up to three litters in one year, each ranging between 1-7 young and averaging 3.4-4.24 young. Philander opossum individuals weigh approximately 9 g at birth and 50-75 g at weaning. The period between litters averages 90 days, and the ovarian cycle is interrupted by lactation, but not gestation. Weaning occurs at day 76 after birth, on average. Female P. opossum reach sexual maturity at 5-8 months in the wild and 15 months in captivity.

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

Few studies have been performed on P. deltae parental investment, but Philander opossum young stay in the nest 8-15 days post-weaning, and after this period the female is indifferent or aggressive to her young.

• Parental Investment
• altricial altricial
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Little is known about the lifespan of P. deltae , but the average lifespan of Philander opossum is 2.5 years in the wild and 3.5 years in captivity.

Behavior

Species of the genus Philander are agile, quick opossums that are good climbers and swimmers, although they are mostly terrestrial. They are nocturnal and solitary. They act aggressively when threatened, and will open their mouths, hiss, and fight in response to threats. Little is known about nest building in this species, but a closely related species, Philander opossum , builds its nests on the ground, in burrows, or in low branches.

• Key Behaviors
• scansorial
• terricolous
• nocturnal nocturnal
• motile motile
• solitary solitary

Home Range

Little information is known about the home range of P. deltae , but P. opossum individuals are non-territorial, have home ranges that overlap, and 137-191 P. opossum can be found in one km^2. Philander opossum individuals also migrate and will stay in one area for less than a year.

Communication and Perception

Although little is known about P. deltae communication and perception, it is known that the closely related P. opossum uses at least three sounds to communicate: a clicking sound, a hiss when threatened, and a squeak, which may be used as a mating call by females. The eyes, ears, nasal turbinates (thin bones that support olfactory epithelium), and tactile hairs are well developed in this species (as in other opossums), so vision, hearing, and touch are probably important senses. Which of these senses is actually used for communication is unknown.

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

Food Habits

Few studies exist on the feeding habits of P. deltae , but species in the genus Philander are omnivores, consuming small mammals, birds and their eggs, reptiles, amphibians, insects, freshwater crustaceans, snails, earthworms, fruits, and carrion.

• Primary Diet
• omnivore omnivore

Predation

There are no known predators of P. deltae , but, like the closely related Philander opossum , it is most likely preyed upon by wild felids, wild mustelids, foxes, large owls, and large snakes. In fact, remains of P. opossum have been found in the feces of the viper Bothrops asper . Opossums of the species P. opossum are also occasionally consumed by humans in Guyana, and P. deltae could also be a food source for humans.

Ecosystem Roles

Species in the genus Philander have been known to host many endoparasites including viruses, protozoans, fungi, roundworms (Nematoda), flukes (Trematoda), and tapeworms (Cestoda) and ectoparasites including lice (Mallophaga), fleas (Siphonaptera), mites, ticks, and chiggers (Acarina). Philander species are also a known reservoir for Trapanosoma cruzi , which causes trypanosomiasis in humans and animals.

In addition, since Philander species consume fruits, are mostly terrestrial, and move often, they are potential dispersers of seeds. One study by Medellin (1994) did find that the closely related Philander opossum does disperse seeds of Cecropia obtusifolia , a tree species important in succession of forests, into adequate germination sites such as light gaps, which other arboreal frugivores do not reach.

Economic Importance for Humans: Positive

It is unlikely that this species is of any positive economic importance for humans.

Economic Importance for Humans: Negative

Philander deltae is unlikely to have a negative economic impact, but Philander species are a known reservoir for Trapanosoma cruzi , which causes trypanosomiasis in humans and animals.

Conservation Status

Philander deltae is listed as a species of least concern by IUCN Red List. Its habitat is extensive with low disturbance by humans and presumably has a large population size. It is also found in at least three protected areas: Guaripiche Forest Reserve, Mariusa National Park, and Delta del Orinoco Biosphere Reserve.

Other Comments

All species in the genus Philander were long considered subspecies of Philander opossum , including Philander deltae . Thus, current species-specific research on P. deltae focuses on morphological and genetic differences between this species and the others in its genus, and most older information is classified under P. opposum. Little information currently exists that differentiates P. deltae from P. opossum in behavior, reproduction, feeding habits, and habitat selection.

Additional Links

Encyclopedia of Life

Contributors

Rachel Cable (author), Animal Diversity Web Staff.

References

D'Andrea, P., R. Cerqueira, E. Hingst. 1994. Age estimation of the Gray Four Eyed Opossum, Philander opossum . Mammalia , 58/2: 283-291.

Hershkovitz, P. 1997. Composition of the family Didelphidae Gray, 1821 (Didelphoidea: Marsupalia), with a review of the morphology and behavior of the included four-eyed pouched opossums of the genus Philander Tiedmann, 1808. Fieldiana: Zoology , 86: 1-103.

Lew, D., R. Pérez-Hernández, J. Ventura, E. Gutiérrez. 2011. "IUCN 2012: The IUCN Red List of Threatened Species" (On-line). Philander deltae . Accessed April 02, 2013 at www.iucnredlist.org .

Lew, D., R. Pérez-Hernández, J. Ventura. 2006. Two New Species of Philander (Didelphimorphia, Didelphidae) from Northern South America. Journal of Mammalogy , 87/2: 224-237.

Medellín, R. 1994. Seed Dispersal of Cecropia obtusifolia by Two Species of Opossums in the Selva Lacandona, Chiapas, Mexico. Biotropica , 26/4: 400-407.

Nowak, R. 2005. Walker's Marsupials of the World . Baltimore: The Johns Hopkins University Press.

Patton, J., M. da Silva. 2007. Genus Philander Brisson, 1762. Pp. 27-35 in Mammals of South America . Chicago: The University of Chicago Press.

Voss, R. 2013. Opossums (Mammalia: Didelphidae) in the diets of Neotropical pitvipers (Serpentes: Crotalinae): Evidence for alternative coevolutionary outcomes?. Toxicon , 66: 1-6.