The complete mitochondrial genome of the firefly, Curtos costipennis (Coleoptera: Lampyridae)

Abstract

We report the complete mitochondrial genome of firefly, Curtos costipennis. The circular genome of 16,626 bp and has a base composition of A (44.44%), C (11.36%), G (7.61%), and T (36.58%). Our sequence is similar to other Metazoa, which contains 13 protein-coding genes. All 13 protein-coding genes were initiated by the ATN (ATT, ATA, and ATG) codon. Nine protein-coding genes stopped with TAA or TAG codon and the other four genes have an incomplete termination codon, a single T. We sequenced the mitochondrial genome of fireflies to analyze phylogenetic relationships and deduce the evolution of their flashing signals

Keywords:

• Curtos costipennis
• firefly
• Lampyridae
• mitochondrial genome

Introduction

The genus Curtos was established by Motschulsky (1845) including 19 species distributed in the southeastern Asia (Fu et al. 2012). In this genus, only four species are widely distributed in China, they are Curtos costipennis (Gorham), Curtos mundulus (Olivier), Curtos sauteri (Olivier), and Curtos sp (Fu 2014). Here, we focus on C. costipennis, through morphological analysis, it is distinguished from congerner by the distinctive yellowish-brown coloration and its smaller size (4–5 mm) (Jeng et al. 1998; Fu 2014).

Mitochondrial genome sequences are essential to a comprehensive understanding of the evolution of Lampyridae and other luminescent beetles (Ermakov et al. 2006). Here, we elucidate the mtDNA genome of C. costipennis.

Specimens used in this study were collected from Mufu Mountain, Gulou District, Nanjing City, Jiangsu Province (32°12′N, 118°78′E) and were stored in Natural History Museum, Huazhong Agricultural University, Wuhan, Hubei, China (its accession no. CC2016062905).

Specific primers were designed based on these conserved regions sequences. The PCR reaction was carried out with LA Taq polymerase for 35 cycles at 94 °C for 30s and annealed at 50 °C for 30s, followed by extension at 72 °C for 1 min per 1 kb. Sequences were assembled using the software DNAstar v7.1 (DNAstar, Madison, WI) and adjusted manually to generate the complete sequence of mitochondrial DNA.

The complete mitochondrial genome sequence of C. costipennis (GenBank:MK609965) has 16,626 bp and has a base composition of A (44.44%), C (11.36%), G (7.61%), T (36.58%). Similar to other Metazoa, our sequence contains 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, a non-coding AT-rich region, which represents a typical insect mitochondrial genome (Wolstenholme 1992). The open frames of the 13 protein-coding genes were inferred from three other fireflies: Aquatica leii, Luciola substriata, and Pyrocoelia rufa (Lee et al. 2004; Jiao et al. 2015; Mu et al. 2016). All 13 PCGs initiated with ATN (ATT, ATA, and ATG) codon. Among those genes, six PCGs (COII, COIII, ND4, ND4L, ATP6, CTYB) initiated from ATG and three PCGs (ND5, ND6, ATP8) initiated from ATT, and four PCGs (COI, ND3, ND1, ND2) initiated from ATA. In addition, an incomplete terminal codon, namely single T was found in four PCGS (COII, COIII, ND5, ND4), In case of other nine PGGS, TAA (ND2, ND6, ATP8, ATP6, ND4L, CTYB, COI) or TAG (ND1, ND3) was used.

The phylogenetic tree among the 12 species based on mitochondrial genome sequences were aligned in MEGA 5 (Phoenix, AZ) (with 1000 bootstrap replicates) to construct a neighbour-joining tree (Figure 1). The result shows C. costipennis is most closely related to Asymmetricata circumdata, which also belongs to the genus of Asymmetricata in the Lampyridae.

Figure 1. Molecular phylogeny of C. costipennis and 11 other firefly species based on the complete mitochondrial genome. The complete mitochondrial genome was downloaded from GenBank and the phylogenic tree was constructed by neighbour-joining method with 1000 bootstrap replicates. MtDNA accession numbers used for tree construction are as follows: Pteroptyx maipo (MF686051) Aquatica ficta (KX758085), Pyrocoelia rufa (AF452048), Aquatica leii (KF667531), Aquatica wuhana (KX758086), Luciola cruciata (AB849456), Asymmetricata circumdata (KX229747), Aquatica lateralis (LC306678), Abscondita anceyi (MH020192) and Luciola substriata (recently identified as Sclerotia flavida by Ballantyne et al. 2016) (KP313820).

In conclusion, the complete mitochondrial genome sequence provides an important molecular framework for further phylogenetic analyses of fireflies.

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the article.

Additional information

Funding

This research was supported by the National Natural Science Foundation of China [#31672349 and #31872281].