Complete mitochondrial genome of nipa palm hispid beetle Octodonta nipae Maulik (Coleoptera: Chrysomelidae: Cassidinae)

Abstract Octodonta nipae (Maulik 1921) is a dangerous forestry quarantine pest, which mainly harms palms. In the present study, we determined complete mitogenome of O. nipae. This mitogenome was 15,397 bp in length (GenBank Accession no. MW802252), which contained 2 ribosomal RNA genes, 22 transfer RNAs, 13 protein-coding genes (PCGs) and one non-coding AT-rich region with the length of 883 bp. All of the 22 tRNA genes displayed a typical clover-leaf structure, with the exception of tRNAPhe, tRNALeu, tRNAAsn, tRNAPro and tRNAThr. Twelve PCGs were initiated by ATN codons, and NAD1 started with TTG. Ten PCGs used the typical stop codon ‘TAA’ and ‘TGA’, while three PCGs (COX2, COX3, NAD4) used the incomplete stop codons ‘TA’ or ‘T’. Phylogenetic tree demonstrated that O. nipae belongs to the family Chrysomelidae and closer to the superfamily Cassidinae.

Octodonta nipae (Maulik 1921), a dangerous quarantine pest for forestry originating from Malaysia (Fu et al. 2020). The adults and larvae of O. nipae gather together to feed on young stems, young shoots and heart leaves of palm plants (Yu et al. 2009). Since first discovered in 2001 in China, it has caused serious damage to nursery stock for palm plants, ecological environment, and city afforestation (Fu et al. 2020). To date, no mitogenome has been studied for this beetle.
In this paper, individuals of O. nipae were collected from Xixiu Beach Park in Haikou (110 15 0 36 00 N, 20 1 0 48 00 E), Hainan, China. The specimens were deposited at À20 C in the herbarium of Post-Entry Quarantine Station for Tropical Plant, Haikou Customs District, PR China (Meng Rui, 541946422@qq. com), under the Accession no. IN06091001-0001-0003. Individual hind legs were used to extract DNA. The mitogenome sequence of O. nipae was generated using Illumina HiSeq X TEN Sequencing System and assembled by MitoZ software without parameters .
The complete circular mitogenome of O. nipae had a length of 15,397 bp (Genbank Accession no. MW802252). The nucleotide composition of O. nipae mitogenome was biased toward AT at 74.1%, and the total base composition was 40.0% A, 34.1% T, 9.3% G, and 16.6% C. The circular genome contained two ribosomal RNA genes, 22 transfer RNAs, 13 protein-coding genes (PCGs), and 1 non-coding AT-rich region with the length of 883 bp. The order and orientation of the above mitochondrial genes were typical of other leaf beetle and identical to those of the ancestral insects (Guo et al. 2017;Liu et al. 2018;. Twelve PCGs started with ATN, except that NAD1 initiated with TTG. 10 PCGs used the typical stop codon 'TAA' and 'TAG', while three PCGs (COX2, COX3, NAD4) used the incomplete stop codons 'TA' or 'T'. All of the 22 tRNAs have a typical clover-leaf secondary structure, except for tRNA Phe , tRNA Leu , tRNA Asn , tRNA Pro , and tRNA Thr whose TWC arm formed a simple loop. All tRNAs had normal lengths, which varied from 61 to 70 bp. The 16S rRNA was 1338 bp long with an AT content of 78.6%, while the 12S rRNA was 792 bp long with an AT content of 78.0%. The non-coding region (putative control region) was 883 bp that located between 12S rRNA and tRNA Ile .
The concatenated datasets of the 13 PCGs from mitogenome of 18 Chrysomeloidea species from NCBI were adopted to build phylogenetic tree. Lampyris noctiluca and Photinus pyralisd that from Elateroidea were used as outgroups. The analyses were performed with Bayesian inference in Phylosuite (Ronquist et al. 2012;Zhang et al. 2020). The phylogenetic tree (Figure 1) demonstrated O. nipae belongs to the family Chrysomelidae and closer to the superfamily Cassidinae. In conclusion, the results of this study can pro-vide essential and important DNA molecular data for further phylogenetic and evolutionary analysis of Chrysomeloidea.

Disclosure statement
No potential conflict of interest was reported by the author(s).