A tiny South American marsupial with a look that’s easy to fall for: big dark eyes, a pointed snout, delicate ears, and a soft coat that often appears gray-brown on top with a noticeably pale, “clean” underside. That bright belly is its signature, giving it a two-tone look like it’s wearing a light shirt under a darker jacket. It’s small enough to seem mouse-like at first glance, but it moves and behaves like a miniature tree-roaming opossum—careful, curious, and built for nighttime. And then there’s the tail: thicker at the base than you’d expect, because this species stores extra energy there, turning its tail into a portable reserve for harder times.

Compared with the dwarf fat-tailed mouse opossum, it’s often thought of as the slightly more robust cousin: still small and delicate, but with a bit more presence, and with that pale underside acting as an instant visual clue. The fat tail is shared among a few close relatives, but the white belly makes this one especially distinctive in dim light when you catch it climbing or pausing on a branch. In a group where many species can look similar—small, gray-brown, quick—having a clear color feature helps it stand out, like a natural name tag.

Its lifestyle is a nighttime mix of hunting and careful exploration. After dark, it moves through shrubs, low trees, and tangled plants using nimble hands and feet, often pausing to sniff the air and listen for tiny movements. Food can include insects and other small prey, plus fruit or nectar when available—think of it as a flexible forager that takes what the night offers. Because it’s so small, it can’t afford to be reckless; it tends to stay close to cover, freeze when surprised, and choose routes that let it vanish quickly into leaves and shadows.

Distribution

Country

Population est.

Status

Year

Comments

Argentina

2015

Bolivia

2015

Chile

2015

Peru

2015