Eight new mitogenomes for exploring the phylogeny and classification of Vetigastropoda

Abstract

Vetigastropoda, comprising marine gastropods of both snail-like and limpet-like form, were common during the Palaeozoic and remain so in modern marine environments. The most resolved molecular phylogenetic study to date at the family level in Vetigastropoda was based on molecular data of complete mitochondrial genomes, but only 15 mitochondrial genomes are available and the taxonomic coverage remains insufficient to resolve many systematic questions. Notably, among the vetigastropod superfamilies, 'Trochoidea' is the most diverse, but no mitogenome has been yet published for its representative family Trochidae. We here provided eight newly reconstructed mitogenomes from the following vetigastropods: Angaria delphinus, Phasianella australis, Astralium haematragum, Lunella granulata, Chlorostoma argyrostomum, Omphalius nigerrimus, Stomatella planulata and Variegemarginula punctata. Stomatella planulata is the first available mitogenome for Trochidae. Our analyses of the extended mitogenome dataset show that the two trochoid families Turbinidae and Tegulidae group together, while their relationship to Trochidae (represented by S. planulata) is uncertain. Within the Tegulidae, monophyly of the genus Tegula is not recovered. The analysis with additional fissurelloid mitogenome confirms that within Vetigastropoda this superfamily is a distinct clade. Except for V. punctata the mitogenomes reconstructed show the ancestral gene order for Vetigastropoda. The additional fissurelloid mitogenome reveals that gene order in Fissurelloidea is variable, which might suggest a faster rate of mitochondrial evolution that in turn may cause artefacts in phylogenetic analyses.