Complete mitochondrial genomes from two species of Chinese freshwater crabs of the genus Sinopotamon recovered using next-generation sequencing reveal a novel gene order (Brachyura, Potamidae).

Xing Yuhui,Hou Yue,Zhang Chen,Pan Da,Wang Xiaoqi,Wang Ruoran,Sun Hongying,Zhou Lijun,Zhang Zhang Huilun

doi:10.3897/zookeys.705.11852

Abstract

Recent morphological and molecular evidence has challenged classical interpretations of eubrachyuran phylogeny and evolution. Complete mitochondrial genomes of two species of potamid freshwater crabs, Sinopotamon yaanense and Sinopotamon yangtsekiense were obtained using next-generation sequencing. The results revealed a novel gene order with translocations of a five-gene block and a tRNA gene in comparison to available brachyuran mitochondrial genomes. DNA sequence comparisons position the Potamidae, a primary freshwater crab family, outside of the clade for the traditional heterotreme families, and closer to the clade that includes the thoracotreme families of grapsoid and ocypodoid crabs. Mitogenomic comparisons using rapid next-generation sequencing and a much wider taxonomic sample are required for a high-resolution examination of the phylogenetic relationships within the Eubrachyura.

Highlights

Brachyuran crabs are one of the most species-rich and economically important groups in extant crustaceans with about 7200 species described (Castro et al 2015), of which two major groups, Heterotremata and Thoracotremata, are collectively referred to as the Eubrachyura (Guinot 1977; de Saint-Laurent 1980; Ahyong et al 2007; Tsang et al 2014)
The mNCR consisted of 1231 bp in S. yaanense, whereas it consisted of 1194 bp in S. yangtsekiense (79.3%)
The largest non-coding region between rrnS and trnI was predicted to be the putative mNCR in the two Sinopotamon crab species ranging from 1194 bp (S. yangtsekiense) to 1231 bp (S. yaanense), where the position is similar to that found in Geothelphusa dehaani and other brachyurans

Summary

Introduction

Brachyuran crabs are one of the most species-rich and economically important groups in extant crustaceans with about 7200 species described (Castro et al 2015), of which two major groups, Heterotremata and Thoracotremata, are collectively referred to as the Eubrachyura (Guinot 1977; de Saint-Laurent 1980; Ahyong et al 2007; Tsang et al 2014). Mitochondrial genome (mitogenome) contains rich signals from both sequence and arrangement of 13 protein-coding genes (PCG), two rRNA genes, 22 tRNA genes and an AT-rich region (main non-coding region, mNCR) in a closed circular DNA molecule (Boore et al 1998; Boore 1999; Sun et al 2003). They are considered powerful markers for resolving ancient phylogenetic relationships (Boore 1999). Knowledge of mitogenomes from primary freshwater crabs remains scant, and only three species have been sampled (including an incomplete sequence; Segawa and Aotsuka 2005; Ji et al 2014; Wang et al 2016)

Methods

Results

Conclusion