Klossnema viguerasi n. sp. (Nematoda: Oxyuridomorpha: Hystrignathidae) is described from the passalid beetle Antillanax pertyi (Kaup, 1869), endemic to Cuba. The females of K. viguerasi n. sp. are morphologically similar but slightly longer than K. repentina Cordeiro & Artigas, 1983 (1.143 mm vs. 1.000 mm). Both species differ in that K. viguerasi n. sp. has a longer procorpus (139 µm vs. 110 µm), isthmus (39 µm vs. 24 µm), and tail length (28 µm vs. 21 µm). The distance from the vulva to the anterior end is also longer in the new species (0.748 mm vs. 0.650 mm). The males of K. viguerasi n. sp. are larger than K. repentina (0.980 mm vs. 0.800 mm), but their isthmus is shorter (38 µm vs. 48 µm). New features of the cephalic end of both sexes, and copulatory papillae pattern of the males were observed by SEM and the generic diagnosis is emended in order to include such features. The phylogeny of K. viguerasi n. sp. is inferred by the analysis of the D2–D3 domains of the 28S rDNA and the 18S rDNA. This constitutes the first record of the genus Klossnema for the Cuban archipelago and the West Indies.