[Redescription of Helminthoxys tiflophila and consideration of the systematics of Oxyuridae parasites of rodents].

--Morphology--Helminthoxys tiflophila (Vigueras, 1943) parasite in Capromys prehensilis (Caviomorpha, Rodent) is redescribed. In the males of this species occurs a peculiar type of ventral cuticular swellings. The adherence with cuticula of females is not obtained by hooking, but by gluing: a ventral hypodermal secretion coagulates on surface of swellings. --Systematic--The genus Helminthoxys Freitas, Lent and Almeida, 1937 is compared by means of cladistic method with the most closely related forms: 1--The genera Helminthoxys and Octodonthoxys Quentin, Courtin and Fontecilla, 1975 cannot be distinguished using this method, 2--Helminthoxys-Octodonthoxys is the sister group of Wellcomia, Sambon 1907, Protozoophaga Travassos, 1923. 3--These four genera, all parasite in Hystricognathi Rodents may be opposed as a sister-group to the Oxyuridae parasite in Sciurognathi Rodents and Lagomorpha. 4--The whole Oxyuridae parasite in Rodents (excepted Citellina Prendel, 1948) and Lagomorpha form a monophyletic group.