The mitochondrial genome of Hercostomus brevipilosus (Diptera: Dolichopodidae).

The long-legged fly Hercostomus brevipilosus (Genbank accession number: MN840034) belongs to the subfamily Dolichopodinae of Dolichopodidae. The mitogenome of H. brevipilosus was sequenced, the first representative of the mitogenome of the genus Hercostomus. The mitogenome is 15,019 bp totally, consisting of 13 protein-coding genes, two rRNAs and 22 transfer RNAs. All genes have similar locations and strands with that of other published species of Dolichopodidae. The nucleotide composition biases toward A and T, which together made up 73.9％ of the entirety. Bayesian inference analysis strongly supported the monophyly of Dolichopodidae and Dolichopodinae. It suggested that Hercostomus is the sister group of Dolichopus.

Hercostomus Loew, 1857 belongs to the subfamily Dolichopodinae. It is a larger genus of Dolichopodidae with 483 known species in the world (Yang et al. 2006, 2011; Grichanov 2017).

The adult specimens of Hercostomus brevipilosus (Genbank accession number: MN840034) used for this study were collected from Qinv Peak (36°31′14″N, 114°38′29″E, 1200 m) of Hebei Province in China in 2016. The specimens of H. brevipilosus were deposited in the Entomological Museum (Accession Number: D-HER-1) of China Agricultural University (CAU). The total genomic DNA was extracted from the whole body (except head) of the specimen using the QIAamp DNA Blood Mini Kit (Qiagen, Germany) and stored at −20 °C until needed. The nearly complete mitogenome of H. brevipilosus is 15,019 bp. It encoded 13 PCGs, 22 tRNA genes, two rRNA genes and the control region could not be sequenced entirely in this study, and were similar with related reports before (Kang et al. 2014; Li et al. 2016, 2017; Wang, Ding, et al. 2016; Wang, Li, et al. 2016; Wang, Liu, et al. 2016; Wang, Wang, et al. 2016; Zhou et al. 2017; Qilemoge, Gao, et al. 2018; Qilemoge, Zhang, et al. 2018; Hou et al. 2019; Qilemoge, Zhang, et al. 2019; Qilemoge, Lin, et al. 2019). The nucleotide composition of the mitogenome was biased toward A and T, with 73.9% of A + T content (A = 38.9%, T = 35.0%, C = 15.4%, G = 10.7%). The A + T content of PCGs, tRNAs, and rRNAs is 72.2%, 75.9%, and 78.6% respectively. The total length of all 13 PCGs of H. brevipilosus is 11,189 bp. All PCGs in H. brevipilosus utilize the conventional translational start codons for invertebrate mtDNA. For example, six PCGs (COII, COIII, ATP6, ND4, ND4L and CYTB) initiated with ATG codons, four PCGs (ND2, ND3, ND5 and ND1) initiated ATT codons, ATP8 initiated ATA codons, ND6 initiated ATC codons, COI initiated TCG codon. Eleven PCGs used the typical termination codons TAA and two PCGs (CytB and ND3) used TAG in H. brevipilosus.

Phylogenetic analysis was performed based on the nucleotide sequences of 13 PCGs and 2 rRNAs from 16 Diptera species. Bayesian (BI) analysis (Figure 1) showed that monophyletic Empidoidea was assigned to be the sister group to the clade of Xylophagidae and Asilidae. For the phylogeny of Empidoidea, monophyletic Empididae was assigned to the sister of monophyletic Dolichopodidae. The phylogenetic relationship within Empidoidea is very clear: Empididae + ((Hydrophorinae + Sympycninae) + (Dolichopodinae + (Sciapodinae + (Diaphorinae + (Rhaphiinae + Medeterinae))))). The position of Hercostomus was assigned to the sister of Dolichopus. The mitogenome of H. brevipilosus could provide the important information for the further studies of Dolichopodidae phylogeny.

Figure 1.

The phylogenetic tree of Bayesian interface analysis based on 13 PCGs and 2 rRNAs from 16 species.