The complete mitochondrial genome of Eristalinus viridis (Coquillett, 1898) (Diptera: Syrphidae) and its phylogenetic implications.

The complete mitochondrial genome of Eristalinus viridis (Coquillett, 1898) was obtained for the first time using Next Generation Sequencing (NGS). The mitogenome assembly of E. viridis is 15,640 bp in length and its annotation confirms the presence of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one putative control region. The results of the phylogenetic analyses using Maximum Likelihood and Bayesian inference recover a highly supported sister relationship between E. viridis and Mallota bellus.

The family Syrphidae, commonly known as hoverflies, is one of the largest and most diversified Diptera groups, with over 6200 recorded species (Evenhuis and Pape 2021). Members of the genus Eristalinus of the subfamily Eristalinae (Diptera, Syrphidae) are important pollinators and are widely distributed in all biogeographic regions (Sonet et al. 2019; Rossi Rotondi et al. 2020). The species Eristalinus viridis (Coquillett, 1898) has a black-green body with metallic green reflections, which is the only one without any spotted or striped compound eyes in the genus Eristalinus (Huo et al. 2007). Here, we obtained the complete mitogenome data of E. viridis and inferred its phylogenetic relationships with other Eristalini members based on mitochondrial genomes.

The specimens of E. viridis were collected in the Changqing National Nature Reserve (107°17’E, 33°19′N) and deposited in the Museum of Zoology and Botany, Shaanxi University of Technology, Hanzhong, China (https://www.snut.edu.cn/, L, Zhao, Lezhao@snut.edu.cn) under the accession no. SYY20190217. The whole genomic DNA was isolated from thorax tissue using the DNeasy kit (Qiagen, Hilden, Germany), and sequenced on Illumina Hi-Seq 4000, paired-end 2 × 150bp at Nextomics Bioscience Company (Wuhan, China). The raw sequence data were quality filtered using the fastp (Chen et al. 2018). The complete mitogenome of E. viridis was assembled and annotated using MITOZ v2.4 (Meng et al. 2019).

The complete mitogenome of E viridis maps as a single circular chromosome and has 15,640 bp in length, with a nucleotide composition rich in T and A (A: 40.9%, T: 37.3%, C: 13.1%, and G: 8.6%). The AT-skew (0.046) was positive and the GC-skew (−0.205) was negative, which is similar to the values reported in other hoverfly mitogenomes (Zhao and Li 2020; Zhou et al. 2021). The typical 37 mitochondrial genes (13 PCGs, 22 tRNAs, and two rRNAs) and one putative D-loop region were found. In addition, ten overlaps and 16 intergenic spacers were found in the mitogenome of E. viridis. The start codon is ATN for most PCGs, but there are five genes with ATG (COX2, COX3, ND4, ND4L, and CYTB), five more genes with ATT (ATP8, ND2, ND3, ND5, and ND6), and two genes with ATA (ATP6 and ND1), whereas COX1 gene uses the alternative CAA. Ten PCGs had TAA as the stop codon, two PCGs (ND1 and ND3) presented TAG, and one (ND5) used the incomplete stop codon TA.

To infer the phylogenetic relationships of E. viridis, we reconstructed the phylogeny of the tribe Eristalini using the concatenated sequence data of 13 PCGs from 22 taxa and two outgroups. The alignment of the PCGs was done using the software MAFFT with the E-INS-I strategy (Katoh and Standley 2013). The maximum-Likelihood (ML) tree and the Bayesian inference (BI) analyses were obtained using the program IQ-tree (Nguyen et al. 2015) and MrBayes (Ronquist et al. 2012), respectively. The phylogenetic trees obtained from the ML and BI analyses presented identical topologies. As shown in Figure 1, . viridis was resolved as a member of the Eristalini, clustered with Mallota bellus Li, 1997 forming a clade with high statistic support. In addition, the monophyly of the tribe Eristalini was well-supported and consistent with previous studies (Moran et al. 2022).

Figure 1.

The phylogenetic tree of the tribe Eristalini based on the 13 mitochondrial protein-coding genes using BI and ML methods. Statistical support values (Bootstrap/posterior probability) of ML/BI methods are shown close to each node.

Ethical approval

Ethics approval was not required for this study. All procedures performed in this study involving animals followed the Guidelines of the Shaanxi University of Technology, Hanzhong, China. The field studies did not include vertebrates, regulated invertebrates, and endangered or protected species.

Author contribution

Le Zhao, Keke Huo, and Gang Li conceived and designed the experiments; Yicheng He and Hanyue Liu performed the experiments; Le Zhao and Yicheng He analyzed the data; Le Zhao, Yicheng He, and Gang Li wrote the paper.