Additional gene data and increased sampling give new insights into the phylogenetic relationships of Neogastropoda, within the caenogastropod phylogenetic framework

Abstract

Neogastropoda, a highly diversified group of predatory marine snails, has often been contradicted in molecular phylogenetic studies. This is partly the consequence of limited neogastropod taxa or outgroups analyzed or insufficient gene sequences employed. This paper reports the most extensive molecular study of the group published to date with increased neogastropod taxa, multiple representatives of caenogastropod outgroups, and additional gene sequences. Data were collected from the entire 18S rRNA, histone H3, and three partial mitochondrial genes. Maximum parsimony, maximum likelihood and Bayesian analyses were conducted. In the caenogastropod phylogenetic framework, Hypsogastropoda was contradicted owing to the inclusion of Cerithioidea. Contrary to previous molecular studies, all the results recovered Neogastropoda as a monophyletic group, which confirms the monophyly of Neogastropoda and the validity of morphological synapomorphies that usually define Neogastropoda as monophyletic. Tonnoidea was shown to be paraphyletic with respect to Ficidae, and together this group formed a monophyletic clade as the sister group to Neogastropoda, which supported the "high mesogastropod" hypothesis of the origin of Neogastropoda. All neogastropod families were strongly supported except Buccinidae, Turridae and Cancellariidae. Our results shed light on the status of Neogastropoda, a controversial group, within Caenogastropoda.