Its species name, macdonnellensis, refers to the MacDonnell Ranges near Alice Springs, where it was first discovered.

[2] The fat-tailed false antechinus is a medium-sized dasyurid marsupial that ranges from 18–33 g (0.63–1.16 oz), and has a life span of about seven years.

An outlying population in more coastal areas of Western Australia has been reclassified as a new species, Rory Cooper's false antechinus (P. roryi).

A characteristic specific to this kind of species is its ability to store fat in its tail when food is plentiful.

[6] In the winter most free ranging P. macdonellensis go into a state of torpor after midnight within the confines of rock crevices, and stay there until day breaks.

[8] Males and females of the subdivision P. macdonellensis reach sexual maturity at about 350 days of age.