Unexpectedly high diversity of lepetodrilid limpets at Indian Ocean deep-sea hot vents sheds light on their global biogeography

Abstract Vetigastropod limpets in the family Lepetodrilidae are endemic to deep-sea chemosynthetic ecosystems, exhibiting a near-global distribution. Their diversity in the Indian Ocean has remained critically understudied despite unidentified specimens known from there for decades. Here, we use an integrative approach to characterize and describe these Indian Ocean vent lepetodrilids, based on material collected from the Carlsberg Ridge (CR), Central Indian Ridge (CIR) and Southwest Indian Ridge (SWIR). We name five new species: Lepetodrilus disco sp. nov. and L. timidus sp. nov. from both the CR and the CIR, L. draco sp. nov. and L. speratus sp. nov. from the SWIR, and Pseudorimula protaspa sp. nov. from both the CR and SWIR. A combination of shell, anatomical and radular characters distinguishes these taxa from their known congeners. Phylogenetic reconstruction using a 1522 bp alignment of the mitochondrial cytochrome oxidase c subunit I (COI) gene demonstrates the radiation of genus Lepetodrilus from the Pacific into the Indian Ocean before colonizing the Atlantic and Southern Oceans. Our results reveal an unexpectedly high diversity in the Indian Ocean and the global vent biogeographic history of genus Lepetodrilus. This highlights the Indian Ocean’s role as a crucial ‘dispersal corridor’ and underscores the urgency for the conservation of vent animals in the face of deep-sea mining threats.