Introduction

Ophiocordycepssinensis(Berk.)G.H.Sung，J.M.Sung，Hywel-Jones& Spatafora(Ascomycota：Ophiocordycipitaceae)is a fungus that parasitizes moth larvae and converts them into sclerotia from which the fungus fruiting body grows(Pegler et al.，1994).The natural O.sinensis，a combination of the fungus and insect larva(Wang，1995)，has been used for centuries as a traditional Chinese medicine for treating asthma，respiratory infection and kidney diseases(Zhu et al.，1998；China，2010).Due to its high commercial value，the species has become endangered in recent years because of overexploitation and habitat degradation(Zhou et al.，2014).The natural O.sinensis population is extremely limited；it is confined to the Tibetan Plateau and its surrounding regions，at elevations of 3000 meters and higher(Li et al.，2011).Therefore，protection of O.sinensis and its host is critically needed(Zhu，2006).Species of Hepialidae(Lepidoptera)have long been considered as the main host insect of O.sinensis based on the geographic distribution，altitude and biological characteristics of the insects.However，there is little information about host identification by molecular analysis.

Due to its unique characteristics，including small genome size，fast evolutionary rate，relatively conserved gene content and organization，maternal inheritance and limited recombination，mitochondrial(mt)DNA has been widely used in phylogeny and evolutionary biology(Saccone et al.，1999；Zhang et al.，2015).To date，282 lepidopteran mt genomes(Exoporia：7，Heteroneura：275)have been deposited in Gen-Bank.Compared with the number of known species of Lepidoptera(180，000 species，http：//www.ucl.ac.uk/taxome/)，the existing molecular information regarding Lepidoptera，especially the Exoporia，is rather limited.The sizes of these 7 Exoporia mt genomes range from 15，064bp to 16，173bp.Their arrangement of tRNA at the junction between the AT-rich region and nad2 is trnI/trnQ/trnM(IQM)，unlike the most common type in other Lepidoptera，trnM/trnI/trnQ(MIQ)(Cao et al.，2012；Chen et al.，2015；Shi et al.，2015；Yi et al.，2016).(https://www.daowen.com)

In this study，we collected the O.sinensis complex of stroma and host cadaver，enriched the mitochondrion of the host cadaver，sequenced the mt genome by a combination of massively parallel DNA sequencing and PCR sequencing，analyzed the complete mt genome of this host cadaver，and constructed the phylogenetic relationship with other Lepidoptera.Clarification of the host insects of O.sinensis will not only provide additional molecular information about Lepidoptera but also provide basic clues for the management of these insect resources and for the conservation and sustainable use of this endangered medicinal species.