Abstract
The Ascaris roundworms (Ascaridida: Nematoda), one of the commonest soil-transmitted helminths (STHs), can cause ascariasis with significant socioeconomic and public health impact. In this study, the mitochondrial genome of Ascaris ovis, a representative of this genus from the sheep in Southwest China was determined using Illumina sequencing technology. The assembled genome was 14,205 bp in size and encoded 36 genes, including 12 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes. Phylogenetic analysis showed that A. ovis grouped with the congeneric Ascaris lumbricoides of humans, Ascaris spp. of non-human primates and Ascaris suum of pigs and together formed a monophyletic group relationship with either species of Baylisascaris/Toxascaris/Parascaris, species of Toxocara, species of Anisakis/Pseudoterranova or species of Ascaridia/Heterakis in the order Ascaridida, supporting its genetic similarity with A. lumbricoides, A. suum, and other congeneric species. The cumulative mitochondrial DNA data of this genus should contribute to a better understanding of the phylogenetic relationships among these roundworms.