Complete mitochondrial genomes of the slugs Deroceras laeve (Agriolimacidae) and Ambigolimax valentianus (Limacidae) provide insights into the phylogeny of Stylommatophora (Mollusca, Gastropoda)

Abstract

In this study, we sequenced two complete mitogenomes from Deroceras laeve and Ambigolimax valentianus. The mitogenome of Ambigolimax valentianus represented the first such data from the family Limacidae. The lengths of the mitogenomes of Deroceras laeve and Ambigolimax valentianus were 14,773 bp and 15,195 bp, respectively. The entire set of 37 mitochondrial genes were identified for both mitogenomes. Compared with the mitogenome of Achatina fulica, the trnP_trnA tRNA cluster was rearranged in both Deroceras laeve and Ambigolimax valentianus. The secondary structures of tRNA and rRNA genes for the two species were predicted. Phylogenetic analyses based on amino acid sequences supported (1) monophyly of Stylommatophora, (2) division of Stylommatophora into the ‘achatinoid’ clade (i.e., the suborder Achatinina) and the ‘non-achatinoid’ clade (i.e., the suborder Helicina), (3) placement of the Orthurethra in the ‘non-achatinoid’ clade, and (4) monophyly of each of the superfamilies Helicoidea, Urocoptoidea, Succineoidea, Arionoidea, Pupilloidea and Limacoidea. The exemplars of Helicidae, Philomycidae and Achatinellidae displayed many more mitochondrial gene rearrangements than other species of Stylommatophora.