Improved phylogenetic resolution within Neritidae (Gastropoda, Nertimorpha) with implications for the evolution of shell traits and habitat

Neritidae is a species‐rich family with substantial interspecific morphological and ecological diversities. The current classification of Neritidae is controversial, particularly regarding the taxonomic position of Smaragdiinae. Although several molecular phylogenetic studies have attempted to clarify the phylogeny of Neritidae, the internal evolutionary relationships have not been completely resolved due to limited sampling. We recently sequenced eight mitochondrial genomes of Neritidae, reassembled five previously published transcriptome data, and reconstructed a comprehensive phylogeny for Neritidae with mitochondrial genome (13 protein‐coding genes) datasets of up to 23 species. Phylogenetic analyses using maximum likelihood and Bayesian inference indicated that the Neritidae were divided into two monophyletic groups, Neritinae and Neritininae, with strong support. A representative of Smaragdiinae, Smaragdia rangiana, was found to nest within Neritininae. Within Neritininae, the monophyly of Clithon and Neritina has not been recovered. Ancestral state reconstruction indicated that the most recent common ancestor of the Neritidae was a smooth shell. Our results imply at least two transitions from marine to brackish habitats within Neritidae.