Abstract Larvae, nymphs and males of Amblyomma pseudoconcolor Aragao, 1908 were collected from a single Zaedyus pichiy (Desmarest, 1804) (Xenarthra: Dasypodidae) captured in the Department of Lavalle (32o49'S 67o51'W), Province of Mendoza, Argentina, which is in the Monte phytogeographical province of the Chaco domain. Ticks were identified using conventional keys and 16S rDNA sequences. This is the most southwesterly collection of A. pseudoconcolor yet obtained and marks a new host record for this species, whose adults typically feed on dasypodids. The range of Z. pichiy in southern South America suggests that the distribution of A. pseudoconcolor is greater than currently realized and probably includes Chile.