A new trochoidean gastropod (Vetigastropoda: Skeneidae) discovered from deep-sea hydrothermal vents in the Southern Ocean

摘要

Hydrothermal vents at the East Scotia Ridge (ESR) were the first vents to be visually confirmed and surveyed in the Southern Ocean. A trochoid snail was recovered from low diffuse flow venting sites of both E2 and E9 segments of the ESR. Taxonomic and systematic investigations revealed it to be a species hitherto unknown to science in the skeneid genus Bruceiella, which is apparently endemic to the chemosynthetic ecosystems. The new species is characterised by a large size for the genus (up to 5 mm shell width), a very broad central tooth with moderately raised horizontal basal ridge, inner marginal teeth with one single prominent protrusion on the shaft, and is described herein as Bruceiella indurata sp. nov. Described members of the genus are known from the Indian and Pacific oceans, drawing interest to the biogeographic origins of the present new species. Closest relative of the present species is Bruceiella wareni Okutani, Hashimoto & Sasaki, 2004 from Kairei vent field, Central Indian Ridge, further indicating the close relationship between East Scotia Ridge and Indian Ocean vent fauna as has been previously suggested.