The Ixodes auritulus complex (Acari: Parasitiformes: Ixodidae) in the Southern Cone of America.

Ixodes auritulus Neumann, 1904 (Acari: Parasitiformes: Ixodidae) represents a species complex principally associated to birds belonging to the orders Ciconiiformes, Charadriiformes, Columbiformes, Falconiformes, Galliformes, Passeriformes, Piciformes, Pelecaniformes, Procellariiformes, Strigiformes, and Tinamiformes in both immature and adult stages. This is a cosmopolitan tick species whose distribution encompass the Afrotropical, Australasian, Nearctic and Neotropical Zoogeographic Regions, and Pacific Oceans islands. Ixodes auritulus sensu stricto was described from southern Chile, and recently new species from this complex were described based only on morphological characters. In this study, specimens of ticks determined to belong to the I. auritulus complex obtained from the Southern Cone of America in different biogeographic regions of Argentina, southern Chile, Brazil and Uruguay were analyzed. Additionally, a female paratype of Ixodes rio Apanaskevich & Labruna, 2022 from the southern from Brazil was included in the study. Morphological characters were analyzed and phylogenetic analyses were performed by obtaining partial mitochondrial DNA sequences of the 16S rRNA and cox1 genes. The specimens from Punta Arenas, Magallanes Province, southern Chile (type locality) correspond morphologically to I. auritulus s.s. and those from central and northern Argentina (Pampa and Yungas Biogeographic Provinces), Uruguay and southern Brazil (Pampa Biogeographic Province) were morphologically compatible with I. rio. The phylogenetic analysis based on mitochondrial DNA sequences support the classification of I. auritulus s.s. from southern Chile and I. rio from Argentina, Brazil and Uruguay as two distinct species. Additional morphological and molecular analyses of ticks from ecological regions other than those included here are necessary to deepen the knowledge of the diversity of the I. auritulus complex in the Southern Cone of America.