First record of the avian ectoparasite Philornis downsi Dodge & Aitken, 1968 (Diptera: Muscidae) in Argentina.

Species of Philornis Meinert, 1890 (Diptera, Muscidae) are Neotropical dipterans that include species with parasitic larvae which feed on nestling birds. To date, all Philornis species that have been recorded from Argentina have parasitic subcutaneous larvae. Here, for the first time for Argentina, we report the finding of Philornis downsi Dodge & Aitken, 1968, a fly with a nest-dwelling, semi-haematophagous larva. This record, from the humid Chaco ecoregion of Argentina in the nest of a saffron finch Sicalis flaveola pelzelni Sclater, substantially extends the known distribution of this species. We also report the consensus sequences of the internal transcribed spacer 1 (ITS1) and ITS2 regions of three of the specimens for future reference and comparison. Further investigation is needed to determine whether Argentina is part of the historical range of P. downsi or, alternatively, represents a recent expansion of its range, perhaps due to climatic changes or other factors of global environmental variation.