A complete mitochondrial genome from Echinochasmus japonicus supports the elevation of Echinochasminae Odhner, 1910 to family rank (Trematoda: Platyhelminthes).

The complete mitochondrial (mt) genome of the trematode Echinochasmus japonicus Tanabe, 1926 was fully determined and annotated. The circular mt molecule of this species is 15,865bp in length, containing 12 protein-coding genes (arranged in the following order: cox3-cob-nad4L-nad4-atp6-nad2-nad1-nad3-cox1-cox2-nad6-nad5), two ribosomal RNA genes (rrnL and rrnS) and 22 transfer RNA genes (trnH; trnQ; trnF; trnM; trnV; trnA; trnD; trnN; trnP; trnI; trnK; trnS1(AGN) ; trnW; trnT; trnC; trnL1(CUN) ; trnS2(UCN) ; trnL2(UUN) ; trnG; and trnE). The atp8 gene is absent. The 3' end of nad4L overlaps the 5' end of nad4 by 40bp. An array of eight identical tandem repeats (240bp each) was found between trnG and trnE in the long non-coding region of the individual worm sequenced. Numbers of these repeats varied among E. japonicus samples. Phylogenetic analysis of concatenated mt protein sequences of 40 trematode species/strains supports the elevation of Echinochasminae Odhner, 1910 to family rank, close to the families Echinostomatidae and Fasciolidae. As echinochasmid and echinostomatid species can parasitize humans, the future characterization of additional mt genomes is needed for development of mt markers for identification and phylogenetic, population, epidemiological and hybridization studies.