First record of a mixed species association between Hatinh langur ( Trachypithecus hatinhensis ) and red-shanked douc ( Pygathrix nemaeus ).

In primates, mixed species associations are not common occurrences, and have been linked to both ecological and anthropogenic factors. We present camera-trapping records of a mixed association between two primates, the Hatinh langur ( Trachypithecus hatinhensis ) and red-shanked douc ( Pygathrix nemaeus ) and discuss possible hypotheses for this occurrence. To our knowledge, this is the first evidence of such an association in the wild of these two threatened primates, and thus contributes to our limited ecological knowledge of the species.