Eight new mitogenomes clarify the phylogenetic relationships of Stromboidea within the caenogastropod phylogenetic framework

Members of the gastropod superfamily Stromboidea (Littorinimorpha) are characterised by their elaborate shell morphologies, distinctive mode of locomotion, and often large and colourful eyes. This iconic group comprises over 130 species, including many large and charismatic species. The family Strombidae is of particular interest, largely due to its commercial importance and wide distribution in tropical and subtropical waters. Although a few strombid mitochondrial genomes have been sequenced, data for the other four Recent families in Strom-boidea are lacking. In this study we report seven new stromboid mitogenomes obtained from transcriptomic and genomic data, with taxonomic representation from each Recent stromboid family, including the first mitoge-nomes for Aporrhaidae, Rostellariidae, Seraphsidae and Struthiolariidae. We also report a new mitogenome for the family Xenophoridae. We use these data, along with published sequences, to investigate the relationships among these and other caenogastropod groups. All analyses undertaken in this study support monophyly of Stromboidea as redefined here to include Xenophoridae, a finding consistent with morphological and behav-ioural data. Consistent with previous morphological and molecular analyses, including those based on mitoge-nomes, monophyly of Hypsogastropoda is confirmed but monophyly of Littorinimorpha is again rejected.

Automated summary

This study reports seven new stromboid mitogenomes, including the first mitogenomes for some Recent families, and investigates the relationships among these groups. All analyses support the monophyly of Stromboidea as redefined to include Xenophoridae, but reject the monophyly of Littorinimorpha, consistent with previous studies.