It is found in moist montane forest in the Atlantic Forest region of southeastern Brazil, including the states of Minas Gerais, Rio de Janeiro, São Paulo and Paraná.

[3] It is considered monotypic and analysis of mtDNA sequences has distinguished this species from other Marmosops.

Early research identified M. paulensis as a subspecies of M. incana.

The name M paulensis came from a mistaken attribution of the species origin as São Paulo.

Subsequent research has, however, distinguished M. paulensis based on various features like smaller upper canines, absence of palatine fenestrae and longer incisive foramina.