Abstract
Gastropods in the family Provannidae are characteristic members of deep-sea chemosynthesis-based communities. Recently, surveys of hydrothermal vents and hydrocarbon seeps in the western Pacific have revealed a high diversity of provannids, with new discoveries continuing to be made. Here, we report and describe a further new species, Provannaexquisita sp. nov., discovered from the Northwest Eifuku volcano on the Mariana Arc. This new species is distinguished from all other described Provanna species by its exaggerated sculpture characterised by two to three sharply raised, flange-like keels on the teleoconch whorls. The status of P.exquisita sp. nov. is also supported by a molecular phylogeny reconstruction using the mitochondrial cytochrome c oxidase subunit I (COI) gene, which suggested that it is most closely related to a clade of three species described from Okinawa Trough vents including P.clathrata, P.subglabra, and P.fenestrata. Despite being one of the better-explored regions of the world in terms of hydrothermal vent biodiversity, new discoveries like P.exquisita sp. nov. continue to remind us that we are nowhere near fully documenting the species diversity in these unique ecosystems-despite the species being threatened from imminent anthropogenic impacts such as deep-sea mining.