Marcelo Weksler and colleagues removed most of the species then placed in "Oryzomys" from the genus in 2006, retaining only the marsh rice rat and related species, including "O. gorgasi". They also kept "O. curasoae" in the genus and suggested that it may not be distinct from "O. gorgasi". In a 2009 paper, R.S. Voss and Weksler examined the two and concluded that they represented the same species on the basis of direct comparisons and a phylogenetic analysis. The resultant tree placed "O. curasoae" and "O. gorgasi" sister to each other and closer to "O. couesi" than to the marsh rice rat. Accordingly, they placed "O. curasoae" as a junior synonym of the earlier described "O. gorgasi".