Holcosus undulatus, also known commonly as the barred whiptail, the metallic ameiva, and the rainbow ameiva, is a species of lizard in the family Teiidae.

The species occurs in Central America from South Mexico to Costa Rica.

[2] H. undulatus is brown-coloured, with a series of darker zig-zag bars running down the sides, often with light blue and green markings along the sides and underside.

It is similar to the Middle American ameiva (H. festivus).

[2] Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Holcosus.