Distribution. Panarctic (Thorson, 1941: 107). On the European side, it reaches as far south as the northern Rockall Trough in bathyal depths; on the American side, it occurs in similar depths down to New England.
Remarks. Characteristic features of the species are the flexuous axial sculpture, well-marked sinus and smooth, obtuse protoconch (on very well preserved specimens only, fine spiral threads can be seen under the microscope).
The name tenuicostata has been used here because it is in general use for the present species, but it has two older synonyms: P. willei was published the year before, but Friele himself never illustrated the type specimen (originating from Norwegian North-Atlantic expedition st 18 or 40). We have examined these samples and they are conspecific with tenuicostata. Later Friele restricted his own use of willei to a form with stronger axial sculpture and the illustrated specimen of 1879 and 1886 comes from st 312, West of Spitzbergen, 1203 m. See also under O. violacea for the nomenclatorial discussion regarding that name.