Complete mitochondrial genome of cylicocyclus auriculatus: molecular structure and phylogenetic analysis

Cylicocyclus spp. (Nematoda: Strongylida: Cyathostominae) are the common and important parasitic nematodes found in horses and donkeys worldwide. In this study, the complete mitochondrial genome of Cylicocyclus auriculatus Looss 1900, a representative member of this genus from the donkey in Southwest China was determined using the next-generation DNA sequencing technology. The genome was 13,851 bp in size and consisted of 36 genes including 12 protein-coding genes (atp6, cox1-3, cytb, nad1-6 and nad4L), 22 transfer RNA genes and two ribosomal RNA genes (rrnL and rrnS), as well as two non-coding regions. Phylogenetic analysis showed that C. auriculatus and Cylicocyclus insigne Boulenger 1917 were closely related, and then both grouped with other congeneric species and formed a monophyletic relationship with either species of Cyathostomum, Coronocyclus, Cyathostomum, Cylicostephanus or Cylicodontophorus, demonstrating their phylogenetic stability within Cyathostominae. These cumulative mitochondrial DNA data provide novel and useful genetic markers for molecular diagnostic, systematic and evolutionary biological studies of Cyathostominae nematodes.