Darwin's fox (Pseudalopex fulvipes) is one of the least known canids in South America. Wilfred Osgood was one of the first investigators to address the taxonomic relationship of Darwin's fox to its congeners. This fox was thought to be restricted to the island of Chiloe; however, a population was recently reported on the mainland in Nahuelbuta National Park. The current taxonomic designation of Darwin's fox as a subspecies of the chilla fox (P. griseus) does not consider the relevance of this mainland population. One of the initial characters used to determine the presence of Darwin's fox on the mainland was pelage color, since Darwin's fox is darker than both the chilla fox and the culpeo fox (P. culpaeus). Analysis of pelage characters was used to determine its effectiveness in generating phylogenetic hypotheses. This analysis suggests a sister group relationship between Darwin's fox and the Sechura fox (P. sechurae), which is consistent with observations made by Wilfred Osgood in 1943.