also known as the gray rice rat, is a genus of rodent consisting of a single species, E. polius. Discovered in 1912 and first described in 1913 by Wilfred Osgood, it was originally named Oryzomys polius. In 2006, a cladistic analysis found that it was not closely related to Oryzomys or to any other known member of its tribe, Oryzomyini. The Brazilian genus Drymoreomys, named in 2011, is probably its closest relative. Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River in central Peru. A large, long-tailed rice rat, with a head and body length of 138 to 164 mm (5.4 to 6.5 in), it has gray fur, short ears, and well-developed ungual tufts of hair on the hindfeet. Females have eight mammae. The rostrum (front part
