Philander mcilhennyi

Geographic Range

Philander mcilhennyi, McIlhenny's four-eyed opossum, is found in the Amazon Basin in the Ucayali and Loreto Departments of eastern central Peru and in the Acre and Amazonas states of northwestern Brazil. (Patton and da Silva, 1997; Patton and da Silva, 2007)


Philander mcilhennyi is found in dry tropical forests in Peru and in Amazonian terra firme forests in Brazil. They can also be found in inundated forests at the headwaters of rivers. This species is tolerant of human disturbance and has been caught in both undisturbed and disturbed areas, such as gardens and secondary growth forests. (Patton and da Silva, 2007; Patton, et al., 2000)

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. (Hershkovitz, 1997; Nowak, 2005)

Philander mcilhennyi is a relatively large opossum for the Philander genus, with a head and body length of 287-307 mm, tail length of 265-377 mm, and weight 396-640 g. Philander mcilhennyi has long, coarse, dark black hair on the dorsum and shorter dark gray or black hair on the venter which is sometimes silver-tipped. A broad dark band extends down the back, but is not strongly differentiated from the color of the sides. Long guardhairs approximately 18 mm long along the dorsum give a shaggy appearance. The throat, chest, and belly can have white or buff colored spots. The ears are black, with no white spots at the base like P. andersoni. The fore- and hind limbs are brown, except for the forefeet, which are pale. The tail is furred by long black hair 20-25% or more from the base and with lighter pigmentation 40-60% from the distal end. (Hershkovitz, 1997; Patton and da Silva, 1997; Patton, et al., 2000)

The distribution of Philander mcilhennyi does overlap with the distribution of Philander opossum canus, but P. mcilhennyi is larger in body size. (Patton and da Silva, 2007; Patton, et al., 2000)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    396 to 640 g
    13.96 to 22.56 oz
  • Range length
    287 to 307 mm
    11.30 to 12.09 in


Philander mcilhennyi most likely breeds year-round, as females with pouched young have been caught in April and June in Peru and in February, March, July, August, and September in Brazil. Litter size ranged between 4-7 young. (Patton and da Silva, 2007; Patton, et al., 2000)

Little else is known about the reproductive behavior of P. mcilhennyi, 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. 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. (D'Andrea, et al., 1994; Hershkovitz, 1997; Nowak, 2005)

  • Breeding season
  • Range number of offspring
    4 to 7

Few studies have been performed on P. mcilhennyi 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. (Hershkovitz, 1997)

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


Little is known about the lifespan of P. mcilhennyi, but the average lifespan of Philander opossum is 2.5 years in the wild and 3.5 years in captivity. (Hershkovitz, 1997)


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. (Hershkovitz, 1997; Nowak, 2005)

Home Range

Little information is known about the home range of P. mcilhennyi, 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. (Hershkovitz, 1997)

Communication and Perception

Although little is known about P. mcilhennyi 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. (Hershkovitz, 1997)

Food Habits

Few studies exist on the feeding habits of P. mcilhennyi, 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. (Nowak, 2005)


There are no known predators of P. mcilhennyi, 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. mcilhennyi could also be a food source for humans. (Hershkovitz, 1997; Voss, 2013)

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. (Hershkovitz, 1997)

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. (Medellín, 1994)

Commensal/Parasitic Species
  • Nematoda
  • Trematoda
  • Cestoda
  • Mallophaga
  • Siphonaptera
  • Acarina
  • Trapanosoma cruzi

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 mcilhennyi 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. (Hershkovitz, 1997)

Conservation Status

Philander mcilhennyi is considered a species of least concern by IUCN Red List because of its wide distribution, expected large population size, and occurrence in protected areas within its range. (Patton and Bantel, 2008)

Other Comments

All species in the genus Philander were long considered subspecies of Philander opossum, including Philander mcilhennyi. Thus, current species-specific research on P. mcilhennyi 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. mcilhennyi from P. opossum in behavior, reproduction, feeding habits, and habitat selection. (Patton and da Silva, 1997)


Rachel Cable (author), Animal Diversity Web Staff.



living in the southern part of the New World. In other words, Central and South America.

World Map


uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

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.


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.

female parental care

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.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


Living on the ground.


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.

year-round breeding

breeding takes place throughout the year


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

Emmons, L., F. Feer. 1997. Neotropical Rainforest Mammals: A Field Guide, Second Edition. Chicago: The University of Chicago Press.

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.

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., C. Bantel. 2008. "Philander mcilhennyi" (On-line). IUCN 2012: The IUCN Red List of Threatened Species. Accessed April 02, 2013 at

Patton, J., M. da Silva. 1997. Definition of species of pouched four-eyed opossums (Didelphidae, Philander). Journal of Mammalogy, 78/1: 90-102.

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

Patton, J., M. da Silva, J. Malcolm. 2000. Mammals of the Rio Juruá and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244: 1-306.

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