Host range and geographical distribution of Ixodes sigelos (Acari: Ixodidae).

Larvae, nymphs and females of Ixodes sigelos Keirans, Clifford and Corwin (Ixodidae) were collected in 13 localities of the Patagonian region of Argentina parasitizing eight species of sigmodontine rodents. We report for the first time adults of I. sigelos for Argentina. Besides, we extend the southern limit of its geographical distribution, and six species of sigmodontines are added as new host species of I. sigelos (Phyllotis xanthopygus, Euneomys chinchilloides, Calomys musculinus, Reithrodon auritus, Loxodontomys micropus and Eligmodontia morgani). The presence of larvae, nymphs and females on sigmodontines, as well as more than 50% of the individuals engorged, indicate that I. sigelos can develop the complete parasitic phase of its life cycle on these small mammals. The geographical distribution of I. sigelos is restricted to the biogeographical Andean Region in Argentina and Chile.