The complete mitochondrial genome and phylogenetic analysis of Chasmagnathus convexus (Crustacea: Grapsidae)

Abstract

The complete mitochondrial genome of the Chasmagnathus convexus has been determined in this study. The complete genome (mtDNA) was 15,107 bp in length and contained 13 protein-coding genes, 1 rRNA genes, and 22 tRNA genes. The overall base composition of the genome in descending order was 34.2% T, 32.8% A, 20.9% C, and 12.1% G. In 13 protein-coding genes, most of the protein-coding genes start with ATG (COX1, COX2, COX3 and ATP8) and ATT (NAD5, NAD4, NAD4L, NAD6, ATP6 and NAD2), only CYTB, NAD3, and NAD1 genes start with ATA. For the stop codon, only NAD2 end with TAG, the other 12 genes end with TAA. Phylogenetic analysis indicated that C. convexus is closely related to Hemigrapsus penicillatus family. It would be a supplement for the genetic analysis of C. convexus and promote the phylogenesis of Grapsidae.

KEYWORD:

• Chasmagnathus convexus
• mitochondrial genome
• Illumina sequencing

 

Chasmagnathus convexus, is a common crab species of the family Grapsidae. (Shih and Suzuki 2008). In Japan, this crab is commonly called hamagani (Ng et al. 2008). It is distributed across Hainan island, Taiwan, Zhejiang, and other places in the Chinese mainland. This crab has two forms that differ in color, one is olive green and the other is purple (Gray et al. 1850). Differences in diet are believed to be responsible for the color variation between the two forms C. convexus is large, relative to the other related crabs, and can reach 4.5–5.0 cm wide across its carapace (Miyasaka et al. 2007).

Here, for the first time, the complete mitochondrial genome of C. convexus has been determined. The specimen of C. convexus was collected in Zhejiang province, China (122.2°E, 30.3°N) and identified by morphology and deposited in National Engineering Research Center for Marine Aquaculture, Marine Science and Technology College, Zhejiang Ocean University. The total DNA extraction was achieved utilizing the salting-out method (Aljanabi and Martinez 1997) with the muscle. The Illumina HiSeq X Ten platform was used to perform the high-throughput sequence.

The complete mitochondrial genome of C. convexus is 15,107 bp in length (GenBank accession number: M567986). The complete mitochondrial genome has 13 protein-coding genes, 1 ribosomal RNA genes, and 22 transfer RNA genes (tRNA). The nucleotide composition for C. convexus is 32.8% A, 34.2% T, 20.9% C, and 12.1% G. In 13 protein-coding genes, most of the protein-coding genes start with ATG (COX1, COX2, COX3, and ATP8) and ATT (NAD5, NAD4, NAD4L, NAD6, ATP6 and NAD2), only CYTB, NAD3, and NAD1 genes start with ATA. For the stop codon, only NAD2 end with TAG, the other 12 genes end with TAA.

The phylogenetic tree (Figure 1) was constructed based on 13 protein-coding genes of 10 species using the Neighbor-joining method in the program Phylip (Felsenstein 1989). The tree showed that C. convexus is closely related to Hemigrapsus penicillatus. We believe that this result will further supplement the genome information in mitochondria of the family Grapsidae and facilitate the study on population genetic.

Figure 1. The NJ phylogenetic tree for Chasmagnathus convexu and other species using 13 protein-coding genes.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was financially supported by the General Scientific Project of Zhejiang Education Department [Y201840255], the 2017 Scientific Research Startup Foundation of Zhejiang Ocean University [12245090418] and special funds for scientific research of National Marine Public Welfare Industry [201505025-4].