Monodelphis arlindoi is a small opossum recorded in a rainforest survey site. In the Saracá-Taquera National Forest in northwestern Pará, a 2009–2015 small-mammal inventory listed it in both live traps and pitfall traps.
In the author’s specimen description, a grizzled-grey band along the middle of the back contrasts with reddish flanks and extends from behind the ears to the tail base. On the head, the stripe can be narrow and poorly defined in some specimens.
A 2009–2015 survey sampled small mammals in tropical rainforest at the Saracá-Taquera National Forest, across plateau, slope, and valley-bottom topographies. The table lists M. arlindoi in both live traps and pitfall traps, but does not assign the species to one particular topography or forest subtype.
The underparts are grayish cream to yellowish, with a reddish throat and chin. Body fur extends along roughly the basal third of the upper side of the tail.
An extinction-risk assessment has not been added yet.