- Any of several salamanders of the genus <em>Ambystoma</em> of Mexico and the western United States that do not go through metamorphosis, becoming sexually mature while in an aquatic larval form with external gills.
- A urodele or tailed amphibian found in Mexico, which is supposed not to undergo metamorphosis, but to retain its gills throughout life, breeding in the larval state.
- An amphibian of the salamander tribe found in the elevated lakes of Mexico; the siredon.
- An <xref>amphibian</xref> of the <xref>salamander</xref> tribe found in the elevated lakes of <xref>Mexico</xref>, Ambystoma mexicanum.
- larval salamander of mountain lakes of Mexico that usually lives without metamorphosing