is mexican salamanders a neotenic species

Yes, the Mexican axolotl (Ambystoma mexicanum) is a well-known example of a neotenic species. Neoteny is a biological process where an organism retains juvenile features into adulthood. In the case of axolotls, this means they maintain their larval characteristics, like the external gills and lack of limbs (or the presence of underdeveloped limbs), as adults.

This retention of larval features is advantageous for them in their natural habitat, which historically has been the lake systems around Mexico City. These traits allow them to live in water without having to transform into a form that might be better suited for land, such as seen in other salamander species.