Genomic data improves the resolution of the <i>Haminoea</i> (Gastropoda: Heterobranchia: Cephalaspidea) tree of life and helps delineating species

Haminoea Turton & Kingston, 1830 is a radiation of coastal herbivorous snails inhabiting temperate and tropical waters of the Atlantic and Eastern Pacific, with a single species occurring along the temperate Indian Ocean coast of South Africa. Previous assessments of the phylogeny and diversity of Haminoea were limited by sparse molecular sampling (3-5 genes), incomplete morpho-anatomical knowledge, and unresolved nomenclatural issues, resulting in varying estimates of species richness (14-20 species). Here, we use complete mitochondrial genomes and the nuclear ribosomal RNA complex (~17,935 bp), combined with Bayesian and maximum-likelihood phylogenetic analyses, species delimitation (ASAP, bPTP), and detailed morpho-anatomical studies. Our aims are to delineate valid species, unravel their phylogenetic relationships and geographic ranges, and provide a robust framework for future systematics and biogeographic studies of the genus. Integrating molecular data with male reproductive anatomy supports the recognition of 15 species (five in the Eastern Atlantic, one in the Indian Ocean, seven in the Western Atlantic, and three in the Eastern Pacific) and yields fully or nearly fully supported phylogenetic hypotheses. The resulting phylogeny reveals a complex evolutionary history shaped by various past geological and climatic events including the Messinian salinity crisis and Pleistocene glacio-eustatic cycles in the Mediterranean, the uplift of the Isthmus of Panama in the Pliocene, and disruptions of the Benguela Current in southern Africa in the Pleistocene.