Published online by Cambridge University Press: 11 May 2009
The genus Turrisphaera Manton, Sutherland & Oates was described on the basis of material from West Greenland, Resolute Bay and South Alaska (Manton, Sutherland & Oates, 1976). In addition to these localities the genus has later been recorded from New Zealand (Moestrup, 1979) and Denmark (Thomsen, unpublished results). The diagnostic characteristics of the genus are the tower-shaped coccoliths and the small hexagonal crystallites. The two species described, the generic type T. borealis Manton, Sutherland & Oates and T. arctica Manton, Sutherland & Oates (Manton et al. 1976), were distinguished by the mucilage covering of T. arctica, and by a certain difference in the elaboration of the distal part of the coccoliths. Furthermore, in T. arctica the flagellar pole coccoliths were longer than the coccoliths elsewhere on the cell (all coccoliths appear equal in T. borealis), and the crystallites somewhat smaller than those of T. borealis.