Shell microstructures of mussels (Bivalvia: Mytilidae: Bathymodiolinae) from deep-sea chemosynthetic sites: Do they have a phylogenetic significance?

► Shell microstructures as potential taxonomic characters for deep-sea mussels. ► Established bathymodiolin lineages cannot be discriminated with these characters. ► Microstructural features uniformity does not challenge Bathymodiolinae monophyly. ► Neotenous features should be considered in the taxonomic revision of this group.