FIGURES 6–18 in Morphology and taxonomy of Psammodiscus Round & Mann (Bacillariophyceae: Rhaphoneidales) with a description of the new species Psammodiscus calceatus

FIGURES 6–18. Psammodiscus nitidus (SEM). Fig. 6. Complete frustule, view of hypovalve (HV), square is enlarged view in fig. 7. Fig. 7. Valve face, external openings of rimoportula (Ri) and small pore (SP), note small pore located near valve centre. Fig. 8. Mantle, areolae (A) occluded by plated rotae (R) with 2–3 spokes (S). Fig. 9. External view of large valve, note valves in figs 9 and 12 generated from the same cell; rectangle (a) is enlarged view in fig. 10; rectangle (b) is enlarged view in fig. 11. Fig. 10. External openings of small pore (SP) and rimoportula (Ri). Fig. 11. External view of fractured valve; areolae (A) occluded by plated rotae (R) with 3 spokes (S). Fig. 12. Internal view of large valve, rectangle (a) is enlarged view in fig. 13; rectangle (b) is enlarged view in fig. 14. Fig. 13. First rimoportula (Ri1), note rimoportula located near margin. Fig. 14. Second rimoportula (Ri2) and small pore (SP), note both rimoportula and small pore are located near the margin. Fig. 15. Complete frustule, note small pore (SP) located near centre of hypovalve (HV); no rimoportula; square (a) is enlarged view in fig 16; square (b) is enlarged view in fig 18. Fig. 16. Valvocopula (VC) opening (OVC) occluded by ligula (L2B) of second band (2B); epivalve (EV). Fig. 17a. Opposite view from fig. 16; hypovalve (HV), valvocopula (VC) opening (OVC), ligula (L2B) of second band (2B), third band (3B). Fig.17b. Schematic drawing of fig. 17a; Pores (P), note pores of second band are circular holes, pores of third band are triangle. Fig. 18. Second band (2B) opening (O2B); valvocopula (VC) and third band (3B). Note third band either in formation or is eroded. Scale bars = 10 µm (Figs 9, 12, 15), 5 µm (Fig. 6), 1 µm (Figs 7, 8, 10, 11, 16– 18), 0.5 µm (Figs 13, 14).