Caluromys philander

The bare-tailed woolly opossum (Caluromys philander) is an opossum from South America. It was first described by Swedish zoologist Carl Linnaeus in 1758. The bare-tailed woolly opossum is characterized by a gray head, brown to gray coat, orange to gray underside and a partially naked tail. It is nocturnal (active mainly at night) and solitary; there is hardly any social interaction except between mother and juveniles and in mating pairs. The opossum constructs nests in tree cavities, and its litter size ranges from one to seven. Gestation lasts 25 days, and the juveniles exit the pouch after three months; weaning occurs a month later. The bare-tailed woolly opossum inhabits subtropical forests, rainforests, secondary forests and plantations; its range extends from northern Venezuela to northeastern and southcentral Brazil. The IUCN classifies this opossum as least concern. The bare-tailed woolly opossum is one of the three members of Caluromys, and is placed in the family Didelphidae in the marsupial order Didelphimorphia. It was first described by Swedish zoologist Carl Linnaeus as Didelphis philander in the 10th edition of Systema Naturae (1758). It was given its present binomial name, Caluromys philander, by American zoologist Joel Asaph Allen in 1900. A 1955 revision of marsupial phylogeny grouped Caluromys, Caluromysiops, Dromiciops (monito del monte) and Glironia (bushy-tailed opossum) under a single subfamily, Microbiotheriinae, noting the dental similarities among these. A 1977 study argued that these similarities are the result of convergent evolution, and placed Caluromys, Caluromysiops and Glironia in a new subfamily, Caluromyinae. In another similar revision in 2009, the bushy-tailed opossum was placed in its own subfamily, Glironiinae. The following four subspecies are recognized: The cladogram below, based on a 2016 study, shows the phylogenetic relationships of the bare-tailed woolly opossum. The bare-tailed woolly opossum is characterized by a brown to gray coat, gray head, orange to gray underside and a partially naked tail furry at the base. A distinctive, narrow dark brown stripe runs between the eyes and the ears, from the tip of the nose to the back of the ears. Similar but broad streaks run from brown rings around either eye. Grayish fur separates these stripes from one another. Ears are large and almost always hairless. The coat is thick, soft and woolly; the flanks may be grayer than the back. The dorsal hairs continue up to 5–7 centimetres (2.0–2.8 in) onto the tail, after which it is naked, as the name suggests. The tail is dark brown towards the end, spotted with white and dark brown, terminating in a white or yellowish white tip. The size appears to decrease from Venezuela to Suriname; the mean weight is 170 grams (6.0 oz) in Venezuela and 250 grams (8.8 oz) in Suriname. The head-and-body length is typically between 16 and 26 centimetres (6.3 and 10.2 in). The ears measure 3 to 3.5 centimetres (1.2 to 1.4 in), the tail 25 to 36 centimetres (9.8 to 14.2 in) and the hind feet 3.2 to 3.9 centimetres (1.3 to 1.5 in). The dental formula is 5.1.3.44.1.3.4 – typical of didelphids. The bare-tailed woolly opossum is nocturnal (active mainly at night), and thus difficult to observe or capture. Nevertheless, it is one of the very few opossums that have been successfully studied in detail. A study showed that activity of bare-tailed woolly opossums can be affected by the extent of moonlight. While activity in males dropped from new moon to full moon (that is, with increasing exposure to moonlight), activity in females remained largely unaffected. The opossum is arboreal (tree-living) and a good climber. A study showed that the tail, being prehensile, can act as an additional limb for locomotion, avoiding falls and carrying leaves to build nests. It builds nests with dry leaves in tree cavities.