The Unduavi gracile opossum (Cryptonanus unduaviensis) is a species of opossum in the family Didelphidae. It is native to northern Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

, where it has been found in seasonally flooded grassland

Flooded grasslands and savannas

Flooded grasslands and savannas is a terrestrial biome. Its component ecoregions are generally located at subtropical and tropical latitudes, which are flooded seasonally or year-round...

. Some of the specimens recognized by Voss et al. as belonging to this species were previously classified as the unduaviensis or buenavistae subspecies of Gracilinanus agilis.