CONICET | Buscador de Institutos y Recursos Humanos

Host specificity is one of the main features of parasitism. The discovery of highly specific parasite species can offer information on the evolution of their hosts. A recent study showed that the nematodes in the tribe Syphaciini (Syphacinae-Oxyuridae) are highly specific and that their species diversify together with the genus of rodents in the tribe Akodontini (Sigmodontinae-Cricetidae). In this work we advance in the study of the taxonomy of the species of Syphaciini parasitic in rodents of the tribe Oryzomyini (Sigmodontinae-Cricetidae), and analyze their host distribution with the aim of observing the degree of correspondence between parasites and their hosts. Hundred thirty seven specimens belonging to nine species of Oryzomyini from Argentina were studied. These identified and revised Syphaciini species as well as those known from the literature were correlated with the phylogeny of the Oryzomyini proposed by Weksler et al. (2006). Syphacia kinsellai was found in Oligorizomys nigripes, O. flavescens y O. fornesi, and S. venteli was found in Nectomys squamipes, several of which are new host and geographic records. The re-examination of S. venteli specimens found in Melanomys caliginosus in 1969 showed that these should be reassigned to a new species. The seven species of Syphacia known from Oryzomyini rodents to date showed a similar host pattern to those observed in Akodontini rodents, in which each species of Syphacia is associated with one host genus. Future studies that enlarge the host range and include the results of host specificity in an ecological-phylogenetic context will allow us to distinguish and suggest possible co-evolutionary events between Syphaciini nematodes and Oryzomyini rodents. This could support the hypothesis that species of Syphacia are good taxonomic markers of the evolutionary history of rodents in the Sigmodontinae.