Extreme Dominance of Coxiella-like Endosymbionts Reveals a Highly Simplified Microbiota in Argas persicus from Mexico

Ticks of the family Argasidae are nidicolous ectoparasites of considerable ecological and veterinary importance because of their role as reservoirs and vectors of microorganisms. Despite the wide distribution of Argas persicus, information on its associated bacterial microbiome remains limited, particularly in the Americas, and little is known about populations inhabiting livestock-associated peridomestic environments. In this study, we characterized the bacterial microbiota associated with A. persicus from a semi-arid region of northern Mexico using 16S rRNA gene (V3–V4) amplicon sequencing. Ticks were collected from cracks and crevices in wooden structures within a small rustic goat farm, illustrating the ability of this nidicolous species to persist in sheltered livestock-associated environments beyond its traditional association with poultry. Ten pools of internal soft tissues were analyzed. The bacterial community exhibited a highly simplified structure dominated by Proteobacteria (99.69%), particularly Coxiella-like endosymbionts (92.63%). Secondary taxa, including Arsenophonus (6.30%), together with Pseudomonas, Acinetobacter, and Sphingomonas, were detected at low relative abundances. Independent sequence comparisons against the NCBI and EMBL-EBI databases supported a conservative interpretation of the dominant lineage as Coxiella-like endosymbionts rather than confirmed Coxiella burnetii. These findings provide the first characterization of the bacterial microbiome associated with A. persicus in Mexico and suggest that populations inhabiting rustic livestock environments can harbor highly simplified bacterial communities dominated by symbiotic bacteria.