 Eremoryzomys polius , also known as the gray rice rat or the Marañon oryzomys , is a rodent in the tribe Oryzomyini of the family Cricetidae . Discovered in 1912 and first described in 1913 by Wilfred Osgood , it was originally placed in Oryzomys and named Oryzomys polius . In 2006 , a cladistic analysis found that it was not closely related to Oryzomys in the strict sense or to any other oryzomyine then known , so that it is now placed in its own genus , Eremoryzomys . The Brazilian genus Drymoreomys , named in 2011 , is probably the closest relative of Eremoryzomys . Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River in central Peru , but may yet contain more than one species . 
