Underwood’s Spectacled Tegu

Underwood’s spectacled tegu (Gymnophthalmus underwoodi) is a small lizard that seems to be a recent arrival on St. Martin, probably within the last ten to fifteen years. It is named after the influential herpetologist Garth Leon Underwood. Amongst other things, Underwood revised the classification of Anolis lizards in the Lesser Antilles in the late 1950s. Originally just collecting a few specimens for a colleague, he undertook the revision when it became clear that many of the classifications, most dating back to the 1800s required an update. This was in part facilitated by the collection of live specimens, whose distinguishing features were much easier to discern than those of the stuffed museum specimens used in earlier taxonomic efforts.

Underwood’s spectacled tegu is probably originally from South America and likely brought to the Lesser Antilles inadvertently. It is parthenogenic, so all individuals are female and can lay eggs without being fertilized. This, along with its small size, probably contributes to its ability to spread to new islands. This family of lizards is referred to as “spectacled” because they have a transparent lower eyelid, allowing them to see through it even when it is shut.

On St. Martin, this lizard is closest in size to the dwarf geckos and closest in habit to the ground lizard. I have seen them most frequently in grassy lowland areas and rocky beaches (the dwarf geckos generally prefer forest floor leaf litter). The impact of this lizard on native species remains to be seen. In its current habitat, it probably competes primarily with juvenile Ameiva plei for food, while its presence in the forest would put it in competition with the two species of dwarf gecko.

Comments are closed.