Oligoryzomys

In Argentina and Chile, Oligoryzomys longicaudatus and other members of the genus represent the reservoir for the hantavirus strain Andes virus (ANDV) (Wells et al., 1997; Levis et al., 1998; Cantoni et al., 2001). The genus Oligoryzomys is included in the subfamily Sigmodontinae of the family Cricetidae. The genus is placed in the Oryzomyini tribe, first proposed by Oldfield Thomas in the early 20th century. It includes genera that have certain dental features of the upper and lower molars and a long palate which extends past the third molars. More recently, molecular analysis and morphological data has placed the genus in Clade C, alongside Neacomys, Microryzomys and Oreoryzomys. Characteristics that identify this group are broad rostrum; a tail that is longer than its head; and short, broad hind feet. Pygmy rice rats are very small rodents, with a head-and-body length of between 70 and 110 mm (2.8 and 4.3 in) and a tail length of between 85 and 155 mm (3.3 and 6.1 in).