A novel benthopelagic ctenophore from 7,217m depth in the Ryukyu Trench, Japan, with notes on the taxonomy of deepsea cydippids

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Two tentaculate ctenophores were observed floating above the sediment at 7,217 m depth in the Ryukyu Trench, Japan, anchored by a pair of long, flexible filaments emerging from the end of the animal opposite the simple tentacles. Several characters suggest taxonomic affinities to the genus Aulacoctena, and the taxonomic placement of this genus is reviewed and discussed with ref- erence to recently collected material. In the light of this re-examination a new family is proposed to contain the genus Aulacoctena. The exact taxonomic placement of the enigmatic benthopelagic ctenophore species remains pending due to the difficulty of procuring samples from such abyssal depths with the recent loss of the world's only submersible platform rated below 7,000 m—the ROV Kaiko.