Molecular phylogeny of the marine snail genus Haminoea (Gastropoda, Cephalaspidea): A framework to study marine diversity and speciation

Abstract

Haminoea are herbivorous, coastal snails occurring in temperate and tropical waters of the Atlantic and Eastern Pacific oceans, with one species present in temperate South Africa (Indian Ocean). The genus is taxonomically difficult as several available nominal species were introduced based on shell descriptions alone, or described based on subtle differences in morpho-anatomical features, without a phylogenetic molecular framework. Fifteen species are currently accepted as valid in recent scientific literature and field guides (eight Eastern Atlantic, one temperate Indian Ocean, four Western Atlantic and three Eastern Pacific). Here we generate the first complete phylogeny (Bayesian and Maximum Likelihood) of this genus based on multilocus molecular data (COI, 12S rRNA, 16S rRNA, 28S rRNA) using a taxon set accumulated over a period of 15 years, coupled with species delimitation analyses methods (ABGD, ASAP, bPTP) and morpho-anatomical studies. The goal of this study is to provide insights into the taxonomy, phylogenetic relationships and geographical distributions of species while generating a framework for future systematic reviews of the genus, as well as to study speciation and historical biogeography. Our results rendered four possible hypotheses of species diversity: with 14, 15, 19 and 20 candidate species and point to the fact that several taxa presently regarded as valid might be conspecific (e.g. H. orteai–H. templadoi–H. exigua; and H. alfredensis–H. antillarum–H. orbignyana), while highlighting the existence of a complex of four or five species often identified as H. elegans. Pervasive nomenclatural problems in the genus, including with the type species H. hydatis, are highlighted and discussed.