First record of Ixodes uriae White, 1852 (Parasitiformes: Ixodidae) on the great shearwater (Procellariiformes: Procellariidae) in Southern Brazil: a step toward understanding tick-host interactions.

The Great Shearwater, Ardenna gravis, is the largest and most abundant species of procellarid seabirds in the South Atlantic. A specimen of this shearwater was found dead and parasitized by a hard tick on Cima Beach, Santa Catarina State, southern Brazil. Morphological and molecular analyses confirmed the tick's identity as Ixodes uriae. Molecular screening for Rickettsiales and Piroplasmida was conducted, and all results were negative, suggesting no immediate health threats. This study reports the first occurrence of this hard tick species parasitizing A. gravis in southern Brazil, highlighting the ecological and epidemiological implications of this finding. This record contributes to the understanding of tick-host interactions in migratory seabirds and emphasizes the need for further research on the ecological roles and health implications of ectoparasites in these avian populations.