We report the occurrence of the lizard Gymnophthalmus underwoodi in the municipality of Belém, state of Pará, Brazil. This is the first record of that species south of the Amazonas River, probably because of an accidental introduction by ships that dock in Belém, the same pathway suggested for the recent introduction of another species of exotic lizard recently recorded in the city. We also determined the identity of some specimens of Gymnophthalmus from the states of Amapá and Pará through external morphology and molecular data, confirming that, until now, G. vanzoi is the only Gymnophthalmus occurring in the savanna enclaves of those states. Finally, we provide a new distribution map for the species of Gymnophthalmus, including the new occurrence record for G. underwoodi for the state of Pará, where it can be considered as an invasive species.