The Complete Mitochondrial Genome Of The Asian Endemic Species Gyge Ovalis(Shiino,1939)(Isopoda:Epicaridea:Bopyridae)

Up to now,Isopoda with more than 10300 species,which show an amazing ecological diversity and morphological flexibility among crustaceans.The existing 11 suborders of Isopoda,the Cymothoida is a group of uniquely parasitic isopods,mainly includes Cymothoidae that parasitised fishes and Epicarideans that parasitized decapods.In the present study,the Asian endemic species Gyge ovalis(Shiino,1939)of Epicaridea was choosed,the complete mitochondrial genome was sequenced and analyzed of.It is the first time to make the first complete mt genome of Epicarideans known.It is the fifth complete mitochondrial genome sequence record after other fourth isopods,which are Ligia oceanica(Linnaeus,1767)? Eophreatoicus sp ? Limnoria quadripunctata(Holthuis,1949)and Bathynomus sp.The results showed that,the mitogenome of Gyge ovalis is 14268 bp(KY038353)in length,and among them the percentage of every kinds of base is adenine 27.01%,thymine 32.56%,cytosine 17.83%,and guanine 22.60%.Component and order of genes is closely related to model structure of Isopoda,but very different in the quantity of genes.The genome contains 34 genes: 13 protein-coding genes,19 tRNA genes,2 ribosomal RNA genes,and a control region.Three tRNA genes(trn E,trnI,and trnS1)are missing.G.ovalis does not fully follow the positive GC skew for(+)strand genes and a negative GC skew for(-)strand genes as.19 tRNA genes have a common clover-leaf secondary structure,for trnC,this pattern is modified and the DHU-arm is absent.Modified secondary structures that are all characterized by the loss of the DHU-arm were also found in trnC of orther isopoda.The rRNA is 1578 bp in length and contains 2 genes:16s rRNA is 1174 bp and 12 s rRNA is 584 bp in length.There are two long-noncoding regions,one is 121 bp in length located between trnN and 12 s rRNA,and the other is 211 bp in length located between trnW and cytb.The latter is assumed to be the mitochondrial control region.The eleven isopods with the wholeprotein encoding genes from Genbank and Gyge ovalis were determined for phylogeny of isopods.The phylogenic tree was constructed by Maxiumum Likelihood analyses and Bayesian Inference.The results showed that Gyge ovalis isn't sister taxa to the Bathynomus sp.and Eurydice pulchra which in same suborder.This results do not support the hypothesis of Dreyer & W?gele,they think Epicaridea and Cymothoidae are often regarded as sister taxa using 18 S ssu rDNA data and external morphological characters,and hypothesized that the decapod-parasitising bopyrids(epicarideans)evolved from species that parasitised fishes(Cymothoidae).The results may reveal that phylogeny between suborders of the Isopoda,also indicate the gene order evolution in isopods is less conservative compared to other crustaceans.Nevertheless,the accurate phylogenetic relationship among every suborder of Isopoda need more gene data to testify.