Complete mitochondrial genome of the subalpine swordtail butterfly Graphium (Pazala) parus (Nicéville, 1900) (Lepidoptera: Papilionidae)

Abstract

The subalpine swordtail butterfly Graphium (Pazala) parus (Nicéville, 1900) is endemic to the Hengduan Mountains centered in West China, its biological and ecological characters still remain poorly understood. The present study reported the complete mitochondrial genome of this butterfly for the first time, which is the second mitogenome record for subgenus Pazala Moore, 1888. The mitogenome of G. (P.) parus is circular and 15,231 bp in length, and consists of 37 genes, including 13 PCGs, 22 tRNAs, and two rRNAs. The maximal likelihood (ML) tree containing the focal species and 30 other available Papilioninae members placed G. (P.) parus sister to G. (P.) mullah (Alphéraky, 1897) inside tribe Leptocircini, which agrees with the taxonomic characters of this species. The findings of this study added data to the complex genus Pazala and would benefit future evolution and conservation biology investigations.

Keywords:

• Mitogenome
• protein coding genes
• transfer RNA
• ribosomal RNA
• phylogenetic position

The swordtail butterflies of the subgenus Pazala Moore, 1888 (Lepidoptera: Papilionidae) are a complex group of Sino-Himalayan species with morphological resemblance and geographical endemicity (Racheli and Cotton 2009); cryptic new taxa have been reported in very recent years (Hu et al. 2018; 2019). Graphium (Pazala) parus (Nicéville, 1900) is a narrow-ranged species endemic to the Hengduan Mountains of northwestern Yunnan, southeastern Tibet, and western Sichuan of China; as well as the very eastern margin of Kachin State, Myanmar. G. (P.) parus occupies the highest elevation range among all species in genus Graphium, and its biological and ecological characters are still poorly understood (Zhang et al. 2018). Since the mitochondrial genome harbors information related to adaptive evolution and conservation biology, the present study reports the complete mitogenome of G. (P.) parus, which is the second mitogenome published in subgenus Pazala, following the low-altitude species G. (P.) mullah (Alphéraky, 1897) (as Pazala timur) (Chen et al. 2014a).

The sample used in this study was collected from Sancha He (100.237254°E, 27.125564°N, 2,930 m) of Yulong Xueshan, Lijiang, Yunnan, China. The specimen was deposited in the zoological museum (insect collection) of Yunnan University, Kunming, China (specimen number: YNU-LEP-PAP-2018015). Genomic DNA was extracted from the thoracic muscle of a single male adult using phenol-chloroform and isopropanol protocol (Hu et al. 2013) and sequenced on an ABI 3730xl automatic sequencer (Applied Biosystems, CA, USA). Resultant gene fragments were assembled using DNAStar (https://www.dnastar.com/) with G. (P.) mullah (KJ472924) as the reference genome. Protein-coding genes (PCGs), transfer RNA genes (tRNAs) and ribosomal RNA genes (rRNAs) were predicted using the web based MITOS (http://mitos.bioinf.uni-leipzig.de/index.py) (Bernt et al. 2013).

The complete mitogenome of G. (P.) parus is circular and 15,231 bp in length (GenBank accession number: MT198821). The base composition is 40.09% for A, 39.48% for T, 7.85% for G, and 12.22% for C. This mitogenome contains 37 genes, including 13 PCGs, 22 tRNAs, and two rRNAs, plus a non-coding control region. The plus (+) strand encodes nine PCGs (nad2, cox1, cox2, atp8, atp6, cox3, nad3, nad6, and cob), while the minus (−) strand encodes four PCGs (nad5, nad4, nad4l, and nad1). The gene arrangement and character of this genome fit those of Lepidoptera mitogenomes (Kim et al. 2009; Park et al. 2012).

To validate the identity of this mitogenome, a maximum likelihood (ML) phylogenetic tree was reconstructed in MEGA 7.0 with the GTR + I + G model, and a bootstrap analysis with 10,000 replications was employed to test the robustness of the tree (Kumar et al. 2016). Thirty species of Papilioninae with available mitogenomes were used as ingroups in the tree analysis and Parnassius apollo Linnaeus, 1758 (Parnassiinae; KF746065) (Chen et al. 2014b) was chosen as the outgroup. The result shows that G. (P.) parus is sister to G. (P.) mullah and then other Graphium species within Leptocircini. All Graphium species used in this analysis form a monophyletic clade, supported by the maximal bootstrap values (Figure 1).

Figure 1. Maximum likelihood (ML) phylogenetic tree for Graphium (Pazala) parus (Nicéville, 1900) (marked with bold font) and other Papilioninae. Node labels represent bootstrap support values.

Acknowledgments

We thank the Yulong Xueshan Provincial Nature Reserve Administration for assistance on the collection of specimens, and Adam M. Cotton (Chiang Mai, Thailand) for improving the earlier drafts of this article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability

The data that support the findings of this study are openly available in the NCBI GenBank, accession numbers of all data are listed in this article.

Additional information

Funding

This study was funded by the NSFC Program of China [41761011] and the Biodiversity Conservation Program of the Ministry of Ecology and Environment, China (China-BON Butterflies) [SDZXWJZ01013].