The transitional colilargo (Microakodontomys transitorius) also known as the intermediate lesser grass mouse, is a species of rodent in the tribe Oryzomyini known only from two individuals found in the Federal District of Brazil. Although described as a link between oryzomyine and akodontine rodents and placed in its own genus, Microakodontomys, Weksler and coworkers dismissed it as an aberrant Oligoryzomys.