The head and body length of Lyncodon patagonicus ranges from 300 to 350 mm, with the tail adding an additional 60 to 90 mm (Nowak, 1999). Patagonian weasels have a dental formula of 3/3, 1/1, 2/2, 1/1= 28 (Mares, 1989). They have very small ears that are covered by the surrounding fur. Generally, the the fur is whitish with some dark brown and black tones intermixed. From the top of the head to along its backside there is a distinguishable broad white or yellowish band of fur. Lyncodon patagonicus has short legs, a long body, and a short bushy tail (Redford and Eisenberg, 1992).
Average mass: 225 g.
Range length: 300 to 350 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry