Redescription of Syphacia venteli Travassos 1937 (Nematoda: Oxyuridae) from Nectomys squamipes in Argentina and Brazil and description of a new species of Syphacia from Melanomys caliginosus in Colombia.

Syphacia venteli Travassos, Mem Inst Oswaldo Cruz 32:607-613, 1937 is redescribed on the basis of specimens recovered from the type host, Nectomys squamipes (Brants 1827), from Brazil and Argentina. Specimens determined by Quentin (Bull Mus Natl Hist Nat 2:909-925, 1969) as S. venteli from Melanomys caliginosus (Tomes 1860) in Colombia were re-studied and assigned to a new species. In both species, structures such as the shape of the cephalic plate, details and distribution of the submedian papillae and amphids, presence and absence of the lateral and cervical alae, and shape and structure of the accessory hook of the gubernaculum were studied with the light microscope and scanning electron microscope. The present survey is the first detailed study of the species S. venteli since the original description, and the first record of this species from Argentina. Moreover, the present study suggests that the validity of some host species of Syphacia should be questioned and that through of the study of deposited specimens, a more exact number of parasitized host species can be confirmed, contributing to a better understanding of host specificity in this genus.