ERGA-BGE reference genomes of Hyalomma lusitanicum and its obligate Francisella endosymbiont as a genomic resource for One Health research

Abstract

Hyalomma lusitanicum is a characteristic tick species of the western Mediterranean region, with a well-established distribution across the Iberian Peninsula. It is strongly associated with wild ungulates, particularly red deer, as well as livestock, to which it can transmit a wide range of pathogens, including viruses, bacteria, and protozoa. Here, we present three genomic resources for H. lusitanicum: a scaffold-scale nuclear genome, the complete mitochondrial genome, and the complete genome of its associated Francisella bacterial endosymbiont. The nuclear genome assembly spans 1.81 Gb and comprises 59 scaffolds, with a scaffold N50 of 153.6 Mb (L50 = 5) and no gaps, indicating high contiguity and completeness with a gene annotation completeness BUSCO score of 97.1 %. Genome annotation of the nuclear assembly identified 20,638 protein-coding genes, 1,422 non-coding genes, and 5,775 pseudogenes. A total of 18 scaffolds were assembled as putative chromosomes, exceeding the 11 chromosomes inferred as ancestral; however, synteny analyses suggest that several scaffolds likely represent fragmented portions of the same chromosome, probably due to incomplete Hi-C scaffolding. Despite this, the assembly represents one of the most complete tick nuclear genomes generated to date. In addition, we report the complete genome of a Francisella endosymbiont (1.51 Mb, 1,679 genes), characterized by a high proportion of pseudogenes and reduced genome size, consistent with patterns of genome reduction associated with obligate symbiosis. Together, these genomic resources provide a framework to investigate local adaptation and host-symbiont evolution, and to support improved surveillance, control, and management strategies for species of public health relevance.