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| Provanna exquisita Chen & Watanabe, 2022 |
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, Provanna exquisita 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.
Keywords: Deep sea, hydrothermal vent, Mollusca, new species, Provannidae, Western Pacific
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| In situ habitat of Provanna exquisita sp. nov. on the summit of Northwest Eifuku Volcano. A overview of the habitat showing dominance by the deep-sea mussel Bathymodiolus septemdierum B close-up of the mixed provannid aggregation, arrowheads indicate examples of P. exquisita sp. nov. Photos taken by ROV ROPOS on dive #792 in Champagne vent, 21°29.25'N, 144°02.49'E, 1608 m deep. |
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Provanna exquisita sp. nov., type specimens A–D holotype (MNHN-IM-2000-37945), shell height 10.4 mm E–H paratype #1 (NSMT-Mo 79360), shell height 11.6 mm I, J paratype #2 (MNHN-IM-2000-37946), shell height 13.1 mm K, L paratype #3 (NSMT-Mo 79361), shell height 9.4 mm. Scale bar: 1 cm, applies to all parts of the figure. |
Systematics
Subclass Caenogastropoda Cox, 1960
Superfamily Abyssochrysoidea Tomlin, 1927
Family Provannidae Warén & Ponder, 1991
Provanna Dall, 1918
Type species: Provanna lomana (Dall, 1918).
Provanna exquisita sp. nov.
Provanna aff. fenestrata —Giguère and Tunnicliffe 2021: supplementary table S2
Diagnosis: A large Provanna reaching over 13 mm in shell height (exceeds 15 mm if spire intact), teleoconch whorls with two or three sharply raised, flange-like spiral keels crossing with weaker axial ribs to form a regularly latticed sculpture.
Distribution: So far, it is only known from a hydrothermal vent field on the summit of Northwest Eifuku Volcano, Mariana Arc. In addition to the Golden Lips site where specimens were collected, it has also been visually confirmed from the Champagne site 40 m away (Fig. 1B).
Etymology: Exquisita (Latin, feminine adjective in the nominative singular), meaning “inquiring” or “exquisite”.
Chong Chen and Hiromi Kayama Watanabe. 2022. A New provannid Snail (Gastropoda, Abyssochrysoidea) discovered from Northwest Eifuku Volcano, Mariana Arc. ZooKeys. 1112: 123-137. DOI: 10.3897/zookeys.1112.85950
