Phylogenetic position of the deep-sea snail family Haloceratidae and new insights into caenogastropod relationships

ABSTRACT The phylogenetic position of Haloceratidae, a little-known family the subclass Caenogastropoda, is contested due to its extreme rarity in bathyal waters worldwide (c. 800–3,500 m deep). Haloceratids share several morphological and ecological traits with members Vanikoroidea, Tonnoidea, Capuloidea Velutinoidea, were provisionally included Vanikoroidea based on absence certain apomorphic features latter three taxa. Here, we first investigate molecular data from both recognized genera, Haloceras Zygoceras. Reconstruction nuclear mitochondrial gene sequences suggests that Haloceratidae constitute sister clade Capulidae two families collectively form superfamily Capuloidea. This united large, robust Calyptraeoidea, Tonnoidea Neogastropoda. Cypraeoidea, as previously conceived, was found be polyphyletic; propose new concepts Cypraeoidea (including Cypraeidae Ovulidae) Velutinoidea Velutinidae, Eratoidae Triviidae). topology also confirms polyphyly taxa ‘echinospira’ type larvae (Echinospirida). resemblance these polyphyletic highlights parallel acquisition response same selective pressures.