Climacosphenia scimiter, cont. All GU52X-1 except D, GU52U-2 A apical pole of valve, exterior view, showing stria density and spines B detail of valve internal aspect, showing absence of costae C detail of external valve face at basal pole, showing more scattered areolae inside annulus D whole mount of frustule, apical pole, showing spines and girdle bands E–G valvocopulae showing consistently seamless craticular bars. Scale bars: 100 µm (E); 10 µm (A, C, D, F, G); 5 µm (B).