[2] The Spanish zoologist Ángel Cabrera went on to synonymize it with the gray four-eyed opossum.

[1] It was recognized as a distinct species in 2020 following a study of the analysis of the cytochrome b of the holotype and other specimens.

Like all other Philander species, it has two light cream-colored spots above the eyes, and the ears are a similar color.

This species lacks a dark dorsal stripe, seen in P. andersoni, and is generally darker.

[1] The original description of P. nigratus noted that it did have a black dorsal line,[2] but subsequent examinations of the holotype seemed to disagree with this.