The mourning gecko Lepidodactylus lugubris broadly occurs in the Indo-Pacific region and is also recorded from some parts of the insular and coastal Latin America. Despite its presence in a number of localities along coastal Southeast Asia, L. lugubris has not ever been reported from Thailand. We observed several individuals of this gecko on Bulon Le Island in 2012 and 2013, and on this island and Mook Island in 2017. This is the first record of L. lugubris in Thailand. In addition, we examined photographs of this species taken in Southeast Asia and deposited in iNaturalist.org (including ours from this study), and recognized two clones on the basis of dorsal color pattern: triploid clone C from Thailand, India (Andaman Islands), Indonesia, and Malaysia, and diploid clone A from Singapore.