Rice rat: A rodent capable of carrying the types of hantavirus that cause HPS (hantavirus pulmonary syndrome) in the US. The rice rat measures 5 to 6 inches for the head and body, plus a very long 4 to 7 inch tail. Rice rats sport short, soft, grayish brown fur on top, and gray or tawny underbellies. This rat likes marshy areas and is semiaquatic. It's found in the southeastern United States and in Central America. Scientific name: Oryzomys palustris.