Fil: Winter, Marina. Universidad Nacional de Río Negro, Sede Atlántica. Centro de Investigaciones y Transferencia de Río Negro (CONICET-UNRN), Río Negro; Argentina.Fil: Sebastian, Patrick Stephan. Instituto de Investigación de la Cadena Láctea (IdICaL), CONICET—INTA, Ruta 34 km 227, 2300 Rafaela, Santa Fe; ArgentinaFil: Nava, Santiago. Instituto de Investigación de la Cadena Láctea (IdICaL), CONICET—INTA, Ruta 34 km 227, 2300 Rafaela, Santa Fe; ArgentinaFil: Tarragona, Evalina Luisa. Instituto de Investigación de la Cadena Láctea (IdICaL), CONICET—INTA, Ruta 34 km 227, 2300 Rafaela, Santa Fe; ArgentinaFil: Abate, Sergio. Universidad Nacional de Río Negro, Sede Atlántica. Centro de Investigaciones y Transferencia de Río Negro (CONICET-UNRN), Río Negro; ArgentinaThis study presents the molecular detection of Candidatus Rickettsia andeanae and Ehrlichia sp. in Amblyomma pseudoconcolor Aragão, 1908 (Acari: Ixodidae) collected on a large hairy armadillo (Chaetophractus villosus (Desmarest, 1804)). On 12 October 2020, a specimen of C. villosus was found dead on the road in Río Negro province, Argentina. Molecular detection of Rickettsia and Ehrlichia agents was performed amplifying the gltA and 16S rRNA gene, respectively. One tick, determined morphologically and genetically as A. pseudoconcolor, was collected on C. villosus. The rickettsial agent detected in A. pseudoconcolor was identified as Candidatus Rickettsia andeanae. The Ehrlichia sp. strain showed high sequence similarity to different uncultured Ehrlichia sp. detected in horses, capybaras and Ixodes ornithorhynchi from Nicaragua, Brazil and Australia, respectively. The results of this study and previous findings suggest that A. pseudoconcolor may be a potential vector of some Rickettsia and Ehrlichia bacteria of unknown pathogenicity.trueThis study presents the molecular detection of Candidatus Rickettsia andeanae and Ehrlichia sp. in Amblyomma pseudoconcolor Aragão, 1908 (Acari: Ixodidae) collected on a large hairy armadillo (Chaetophractus villosus (Desmarest, 1804)). On 12 October 2020, a specimen of C. villosus was found dead on the road in Río Negro province, Argentina. Molecular detection of Rickettsia and Ehrlichia agents was performed amplifying the gltA and 16S rRNA gene, respectively. One tick, determined morphologically and genetically as A. pseudoconcolor, was collected on C. villosus. The rickettsial agent detected in A. pseudoconcolor was identified as Candidatus Rickettsia andeanae. The Ehrlichia sp. strain showed high sequence similarity to different uncultured Ehrlichia sp. detected in horses, capybaras and Ixodes ornithorhynchi from Nicaragua, Brazil and Australia, respectively. The results of this study and previous findings suggest that A. pseudoconcolor may be a potential vector of some Rickettsia and Ehrlichia bacteria of unknown pathogenicity.