Philander opossum (Linnaeus, 1758)

Astúa, D., 2015, Didelphidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 129-186 : 167

64.

Gray Four-eyed Opossum

Philander opossum

French: Opossum gris / German: Graue Vieraugenbeutelratte / Spanish: Filandro gris

Other common names: Guaiki

Taxonomy. Didelphis opossum Linnaeus, 1758 ,

“America.” Restricted by J. A. Allen in 1900 to “Surinam” and further restricted by P. Matschie in 1916 to “ Paramaribo, Surinam.”

There is great variation in morphology of this species, and several subspecies have yet to be properly studied. The genus is in need of a revision using modern techniques, and status of this species may change. Five subspecies recognized.

Subspecies and Distribution.

P.o.opossumLinnaeus,1758—theGuianas,andN&EAmazonianBrazil.

P.o.canusOsgood,1913—WAmazonBasininBrazil,EPeru,andN&EBolivia,alsoinParaguay(AltoParaguay,PresidenteHayes,Neembucti)andNArgentina(Formosa,Chaco).

P.o.fuscogriseusJ.A.Allen,1900—HondurasSintoN&WColombiaandSalongthePacificlowlandsintoSEcuador.

P.o.melanurusThomas,1899—PacificlowlandsofColombiaandNEcuador.

P.o. pallidus]. A. Allen, 1901 — E & S Mexico (S of Tamaulipas) and N Central America.

Descriptive notes. Head-body 20-33.1 cm,tail 19.5-33.5 cm; weight 200-674 g. Captive specimens, however, can reach 1-5 kg. Dorsal fur in the Gray Four-eyed Opossum varies from pale gray to dark gray, blackish, or even brownish-gray, with no marked mid-dorsal stripe, although some specimens have darker dorsum. There is considerable geographical variation in fur color. Head is same color as dorsum, with large and well-defined pale supraocular spots and spots at bases of ears, but no mid-rostral stripe. Tail length is about equal to head-body length, tail has fur on its proximal 20% or less, and naked part of tail is colored black or dark gray, with pale spots on proximal two-thirds. Tip oftail can be paler, sharply demarcated, or completely dark. Ventral fur is pale yellowish-orange, or pale gray on chest and abdominal region and cheeks and creamy-white on chin. Sternal gland is present. Fur is short, dense, and soft. Ears are large, naked, and pale in center and black on rims. Females have a complete pouch that opens forward, with seven mammae, three on each side and a medial mamma. The Gray Four-eyed Opossum has a 2n = 22, FN = 20 karyotype, with all acrocentric autosomes, and acrocentric X-chromosome and Y-chromosome.

Habitat. Disturbed forests (including second-growth forests, garden plots, orchards, and croplands) and undisturbed humid primary forest, gallery forests, and campo umido in the cerrado. Gray Four-eyed Opossums are often captured near streams and swamps, or in moist areas, but they apparently occur in vegetation types such as deciduous and evergreen forests and also drier habitats such as Chacoan forests.

Food and Feeding. Diet of the Gray Four-eyed Opossum has been well studied in some sites. In French Guiana,its diet includes a high diversity of items, such as earthworms, Coleoptera, Hymenoptera, Isoptera, Odonata, Orthoptera, Chilopoda, Arachnida, snails, and crustaceans. Fruit constitutes ¢.50% ofits diet, including Astrocaryum (Arecaceae) , Attalea (Arecaceae) , Cecropia (Urticaceae) , Clusia (Clusiaceae) , Ficus (Moraceae) , Inga (Fabaceae) , Passiflora (Passifloraceae) , Piper (Piperaceae) , and Virola (Mpyristicaceae) . Most fruits consumed are rich in pulp, and as this pulp is consumed, seeds, especially larger ones, are discarded in place, with only the smaller ones being ingested. Gray Four-eyed Opossums are very opportunistic in fruit consumption, with no limit on size, position in the tree, or nutritional value. The only features present in all fruits they eat are a fleshy pulp, high water content, and no protection. Gray Foureyed Opossums have also been seen feeding on nectar of species of Balanophoraceae and tree exudates, using their teeth to reopen healed openings in tree trunks to renew flow of sap. In Panama, stomach contents revealed consumption of nuts of Elaeis oleifera ( Arecaceae ), insects, freshwater shrimp, a murid rodent, and a Tome’s Spinyrat (Proechimys semispinosus). One individual was seen opportunistically feeding on live bats entangled in mist-nets. Gray Four-eyed Opossums also prey on leptodactylid frogs, locating them acoustically, following their calls. In Nicaragua, one individual pulled a Central American coral snake (Micrurus nigrocinctus) from its burrow and successfully killed it without being bitten. In Mexico, they have been seen feeding on figs dropped by a colony of Artibeus fruit bats.

Breeding. Female Gray Four-eyed Opossums make nests with dry leaves in hollow trees, tree forks, fallen logs, ground burrows, banana and palm trees, house roofs, and traditional houses of indigenous people. Their nests are globular and ¢.30 cm in diameter. Females reach sexual maturity at 6-7 months old and males at c.7 months old. Newborns weigh c.9 g and reach 50-75 g when they are weaned at 68-75 days old. Teeth are fully erupted at c.1 year of age, and individuals live up to c.2-5 years in the wild. Litter size varies somewhat throughout its distribution, but a maximum survivable litter of size of seven young is set by number of available mammae. Mean litter size was 4-6 young (range 2-7 young) in Panama, 4-7 young in Peru, and 4-5 young in Brazilian Amazonia. In French Guiana, 2—4 litters/breeding season have been observed, with birth interval of c.90 days. There is also some variation in timing and extent of breeding season throughout the distribution of the Gray Four-eyed Opossum. In mature forests, breeding has been recorded throughout the year, but in secondary forests, fewer births are recorded during the dry season with less resource availability. In French Guiana, reproduction has been recorded throughout the year, but itis more intense at the peak of fruiting season and decreases toward end of the rainy season. Nevertheless, given the extent of its distribution, breeding seasons have been recorded with different onsets and extents. Gray Four-eyed Opossums breed throughout the year or in February—June in Mexico, February—October in Nicaragua, and February-November in Panama. Breeding individuals were recorded in May—October in Colombia, January-April, and all year long in Peru. In Brazilian Amazonia, females with pouch young were only captured in February-March during the rainy season.

Activity patterns. Gray Four-eyed Opossums are nocturnal, although there are reports of diurnal activity in Suriname.

Movements, Home range and Social organization. Gray Four-eyed Opossums are solitary and are usually captured on the ground, although they occasionally use understory. In Panama, average distances traveled were 60-73 m, up to 125 m. They mostly use the ground and understory, but nests can be found at 8-10 m. They also swim well and apparently frequently, depending on habitat. In Panama, small size of several islands in Gatun Lake on which Gray Four-eyed Opossum were captured strongly suggests that they routinely move from island to island. In Mexico, fleeing individuals were seen intentionally diving into the water and swimming. In the Panama Canal Zone, densities of Gray Four-eyed Opossums were similar in second-growth tropical forest and mature moist tropical forest; highest densities occurred in the dry season at both sites and were 65 ind/km?* and 55 ind/km?, respectively. An average of 137 ind/km? was estimated for a secondary forest site in French Guiana, with monthly averages of 85-180 ind/km?, but lower densities, on average 17 ind/km?, were found in a primary forest also in French Guiana. In Chiapas, Mexico, average density was 48 ind/km®. Home ranges average 0-34 ha in Panama and 0-2 ha in a gallery forest in the Brazilian cerrado, but these are likely to be underestimates, based on home ranges of other species in the genus.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Gray Four-eyed Opossum has a wide distribution and presumably a large overall population. It occurs in several protected areas and is tolerant or even prefers human-modified areas.

Bibliography. Abdala et al. (2006), Adler & Seamon (1996), Adler et al. (2012), Alho et al. (1986), Allen (1900), Aragona & Marinho-Filho (2009), Astua et al. (2001), Atramentowicz (1982, 1986, 1988), Biggers et al. (1965), Carvalho et al. (2002), Castro-Arellano et al. (2000), Catzeflis (2012), Charles-Dominique (1983), Charles-Dominique et al. (1981), Chemisquy & Flores (2012), Diaz (2014), Diaz & Flores (2008), Emmons & Feer (1997), Fleck & Harder (1995), Fleming (1972, 1973), Gardner (2005), Gbmez-Martinez et al. (2008), Grand (1983), Hall & Dalquest (1963), Hamrick (2001), Handley (1976), Herrera (2010), Hershkovitz (1997), Julien-Laferriere (1991), Julien-Laferriere & Atramentowicz (1990), Lambert et al. (2005), Lemelin (1999), Matschie (1916a), McNab (1982, 2005), Medellin (1991, 1994), Medellin et al. (1992), Nunes et al. (2006), Patton & Costa (2003), Patton & da Silva (1997, 2007), Patton et al. (2000), Pereira et al. (2008), Phillips & Jones (1969), Reig et al. (1977), Rocha, R.G. et al. (2011), de la Sancha & D’Elia (2014), Santos-Filho et al. (2008), Sebastiao & Marroig (2013), Tuttle et al. (1981), Voss & Jansa (2012).

Figures

65. Pygmy Opossum (Chacodelphys formosa), 66. Agricola’s Opossum (Cryptonanus agricola), 67. Chacoan Mouse Opossum (Cryptonanus chacoensis), 68. Guaiba Mouse Opossum (Cryptonanus guahybae), 69. Unduavi Mouse Opossum (Cryptonanus unduaviensis), 70. . Emilie’s. 9 Opossum.. Gracilinanus. (null), 71. Aceramarca Opossum (Gracilinanus aceramarcae), 72. Agile Opossum (Gracilinanus agilis), 73. Wood Sprite Opossum (Gracilinanus dryas), 74. Northern Gracile Opossum (Gracilinanus marica), 75. Brazilian Gracile Opossum (Gracilinanus microtarsus)

Subspecies and Distribution. P.o.opossumLinnaeus,1758—theGuianas,andN&EAmazonianBrazil. P.o.canusOsgood,1913—WAmazonBasininBrazil,EPeru,andN&EBolivia,alsoinParaguay(AltoParaguay,PresidenteHayes,Neembucti)andNArgentina(Formosa,Chaco). P.o.fuscogriseusJ.A.Allen,1900—HondurasSintoN&WColombiaandSalongthePacificlowlandsintoSEcuador. P.o.melanurusThomas,1899—PacificlowlandsofColombiaandNEcuador. P.o. pallidus]. A. Allen, 1901 — E & S Mexico (S of Tamaulipas) and N Central America.