The aim of this study is to describe Fannia sanihue sp. nov., a new species of Fanniidae that was captured in the proximity of a pig carcass in the province of Mendoza, Argentina. This contribution is a part of the first study to be undertaken into forensic entomology in the biogeographical province of the Monte, which is a warm shrub desert extending between Puna and Patagonia at the east of the Andes Mountains.