Systematic and distribution of Orihelia anticlava [Molin, 1858] [Nematoda, Onchocercidae] from dasypodids of South America

Among the Dasypodidae (Xenarthra), 5 species are currently known to be hosts of Orihelia anticlava (Molin, 1858) in Brazil, Paraguay and Argentina. We gather all the information regarding taxonomy, morphology, ecology and geographical distribution of O. anticlava, in order to hypothesize on the origin and evolution of this filarioid which is parasitic in an interesting host group, Dasypodidae. An amount of 192 specimens of 9 species of dasypodids from Argentina was prospected. Chaetophractus villosus and Tolypeutes matacus were parasitized. Measurements are provided, and the area rugosa described. Uterine microfilariae of O. anticlava show a considerable range of sizes; length of blood microfilariae seem not to be affected by geography; and, blood microfilariae are bigger than uterine ones. Despite that this parasite occurs in different host species, adult worms studied so far were morphologically alike. Prevalence and mean intensity were: C. villosus 10.8% and 8.5, T. matacus 3.7% and 1. Taking into account the geographic distribution of the hosts and the phylogeny of the dasypodids, we suggest that O. anticlava could be more widespread than currently noticed and other genera of dasypodids, such as Cabassous, Chlamyphorus, and Zaedyus, could also be parasitized. We believe that central Argentina, Uruguay, southern and northeastern Brazil should be considered preferable prospecting areas.