The complete mitochondrial genome of Lymantria xylina with phylogenetic analysis.

Lymantria xylina (Lepidoptera: Lymantriidae) is an important forest pest in some Asian countries. In this study, we determined the complete mitochondrial genome of L. xylina. The length of the genome is 15,488 bp and contains 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and an A + T-rich region. All PCGs use ATN as start codon and TAA as stop codon except for cox2 and nad4. The A + T-content of the genome is 80.64% and show the bias of nucleotides. We reconstructed the sister group relationship of (L. xylina + (L. dispar + Lymantria sp. AN-2017)).

Lymantria xylina is a common pest of forest, natural areas and fruit tree orchard in Taiwan, Japan, India, and the eastern coast of mainland China (Chao et al. 1996). It is an herbivore that feeds on casuarina (Casuarina equisetifolia), guava (Psidium guajava L.), longan (Euphoria longana Lam.), and more than 60 other species of host plants (Shen et al. 2003; Shen et al. 2006). Lymantria xylina is closely similar to Lymantria dispar (L.) on morphology, which is an extremely serious forest pest in North America and is an important quarantine insect in Chinese ports.

Lymantria xylina was collected on Longquan Mountain in Sanming, China (117°28′58.3′′, 25°35′12.8′′) and stored in the Quarantine Insect Herbarium of Zhejiang Academy of Science & Technology for Inspection & Quarantine (ZAIQ) with accession number ZAIQ-LL-SM-1807. We sequenced and annotated the complete mitochondrial genomic DNA. The genome was sequenced using primer walking method and annotated by MITOS WebServer (http://mitos.bioinf.uni-leipzig.de/index.py). The annotation was checked using BLAST and tRNAscan-SE Search Server (Lowe and Chan 2016: Chan and Lowe 2019).

The complete mitochondrial genome of L. xylina (Genbank accession MN038145) is 15,488 bp in length and contains 13 PCGs, 22 tRNA genes, 2 rRNA genes, and an A + T-rich region. 22 genes were encoded on the majority strand and the other 14 were encoded on minority strand. The A + T-content of the whole genome is 80.64%. The AT-skew and GC-skew are 0.0060 and −0.2138, respectively, indicating that more As than Ts and more Cs than Gs are present in the genome. The length of the PCGs range from 168 bp to 1590 bp and the A + T-contents range from 72.06% to 91.67%. All PCGs use ATN as start codon including 5 ATT, 4 ATA, and 4 ATG. All PCGs using TAA as stop codon except for cox2 and nad4. The incomplete stop codon T is commonly reported in other invertebrates (Masta and Boore 2004). The length of the 22 tRNA genes ranges from 63 bp to 71 bp with typical cloverleaf structures. The length of the lrRNA and srRNA is 1365 bp and 796 bp with A + T content of 84.15 and 85.55%, respectively. The length of A + T-rich region is 424 bp with 97.64% A + T content.

The phylogenetic relationship within Lymantriidae was recovered based on 13 PCGs (Figure 1). We reconstructed the sister group relationship of (L. xylina + (L. dispar + Lymantria sp. AN-2017)), which is identical with phylogenetic relationship based on morphology.

Figure 1.

Phylogenetic relationship within Lymantriidae was reconstructed based on 13 PCGs. 19 other mtgenomes were downloaded from NCBI and Papilio xuthus was set as outgroup. The number on each node is the bootstrap value. The GenBank accession numbers are indicated after the scientific name.