Sequencing of the Complete Mitochondrial Genome of Pingus sinensis (Spirurina: Quimperiidae): Gene Arrangements and Phylogenetic Implications

Despite several decades of intensive research on spirurine nematodes, molecular data on some of the main lineages are still absent, which makes taxonomic classification insufficiently resolved. In the present study, we sequenced the first complete mitogenome for the family Quimperiidae, belonging to P. sinensis (Spirurina: Quimperiidae), a parasite living in the intestines of snakehead (Ophiocephalus argus). The circular mitogenome is 13,874 bp long, and it contains the standard nematode gene set: 22 transfer RNAs, 2 ribosomal RNAs and 12 protein-coding genes. There are also two long non-coding regions (NCR), in addition to only 8 other intergenic regions, ranging in size from 1 to 58 bp. To investigate its phylogenetic position and study the relationships among other available Spirurina, we performed the phylogenetic analysis using Bayesian inference and maximum likelihood approaches by concatenating the nucleotide sequences of all 36 genes on a dataset containing all available mitogenomes of the suborder Spirurina from NCBI and compared with gene order phylogenies using the MLGO program. Both supported the closer relationship of Ascaridoidea to Seuratoidea than to Spiruroidea. Pingus formed a sister-group with the Cucullanus genus. The results provide a new insights into the relationships within Spirurina.