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 ( atp 6, cox 1-3, cytb , nad 1-6 and nad 4L), 22 transfer RNA genes and two ribosomal RNA genes ( rrn L and rrn S), 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.