Abstract
Bathysiphon filiformis G.O. & M. Sars in G.O. Sars, 1872, the type-species of the large, tubular, agglutinated foraminiferal genus Bathysiphon, has been confused in the literature with other members of the genus. In order to stabilize this species, a neotype is selected from material collected in the type-area (Hardangerfjord, Norway) and housed in the British Museum (Natural History). Bathysiphon filiformis is redescribed on the basis of this material and also from specimens collected in the bathyal north-east Atlantic by the Institute of Oceanographic Sciences (IOS). A new species, B. hystrix sp. nov., which is closely allied to B. filiformis, is described from specimens in IOS collections.