Falcaustra tannaensis n. sp. (Ascaridida: Kathlaniidae) from the large intestine of Nactus pelagicus (Squamata: Gekkonidae) is described and illustrated. Falcaustra tannaensis represents the first species from Oceanica to be assigned to the genus and is distinguished from other species of Falcaustra by the distribution pattern of caudal papillae (8 precloacal, 2 adcloacal, 10 postcloacal, and 1 median), length of spicules (2.43-2.68 mm), and presence of a pseudosucker.