Aplectana novaeguineae n. sp. (Ascaridida, Cosmocercidae) from the intestines of Sphenomorphus pratti (Squamata: Scincidae) is described and illustrated. Aplectana novaeguineae n. sp. represents the 48th species assigned to the genus and the 5th species of the genus reported from the Australo-Papuan region. It is most similar to Aplectana leesi, Aplectana linstowi, and Aplectana krausi in that females of only these 4 species exhibit a swollen anterior vulvar lip. These 4 species may be separated by spicule length and caudal papillae arrangement. Spicules of A. linstowi and A. krausi are less than 200 µm in length, A. leesi between 200 and 250 µm, and A novaeguineae greater than 400 µm. Aplectana linstowi possesses 18 post cloacal papillae, A. leesi and A. krausi each possess 10, and A. novaeguineae possesses 8. In addition, Paraleptonema ranae has been assigned to Aplectana as Aplectana fujianae nom. nov.