The mitochondrial genome of the gold-ringed cowry Monetaria annulus (Mollusca: Gastropoda: Cypraeidae) determined by whole-genome sequencing

Abstract

The mitochondrial genome of the cowry snail Monetaria annulus (Caenogastropoda: Cypraeoidea: Cypraeidae) was determined by whole-genome next-generation sequencing. The mitogenome is composed of 13 protein-coding genes (PCGs), 2 ribosomal RNA (12S and 16S) genes, and 22 transfer RNA genes (tRNAs). This gene order is consistent with the previously published mitochondrial genomes of other species belonging to the order Littorinimorpha. The superfamily Cypraeoidea was recovered as a sister clade to the group of Tonnoidea and Neogastropoda.

Keywords: Caenogastropoda; Cypraeoidea; Littorinimorpha; next-generation sequencing; phylogenetic tree.

Figure 1.

Maximum likelihood phylogeny of the subclass Caenogastropoda based on mitochondrial amino acid sequences of 13 protein-cording genes from Monetaria annulus (bold, this study; LC469295) and the 117 gastropod species previously published (one neomphaloid, two neritimorph, two vetigastropod, two heterobranch, three patellogastropod, and 107 caenogastropod species). Sequences were aligned separately for each gene using MUSCLE (Edgar 2004) in Translator X (Abascal et al. 2010) with default parameters. Ambiguously aligned positions were removed using Gblocks v.0.91b (Castresana 2000) with an option to allow gap positions in the final blocks for a less stringent selection. Tree reconstruction was performed in RAxML-HPC v.8.2.10 on XSEDE (Stamatakis 2014) using MTRev + G model through the CIPRES Science Gateway (Miller et al. 2010); nodal support estimated by 1,000 thorough bootstrap replicates. Scale bar represents branch length (substitutions/site). Accession numbers are shown in the tree. Asterisks indicate the node with 100% boot-strap probability (BP). BP values for each node were not shown below 70%. The higher classification follows Osca et al. (2015) and Bouchet et al. (2017). The superfamily Cypraeoidea was recovered as a sister group to the clade including Tonnoidea and Neogastropoda, although the bootstrap value was not high (BP = 79%). The superorder Latrogastropoda (Cypraeoidea + Stromboidea + Tonnoidea + Neogastropoda) was monophyletic (88%), as indicated by previous studies (Osca et al. ; Bouchet et al. 2017).