FIGURES 15–21 in Oricymba rhynchocephala sp. nov., a new cymbelloid diatom (Bacillariophyceae) from Xianju National Park in Zhejiang Province, China

FIGURES 15–21. Oricymba rhynchocephala, SEM, external views. 15. Entire valve. Notice the distinct marginal ridge, proximal raphe ends and rounded, single ventrally-placed stigma opening. Striae appear slit-like. Distal raphe ends deflect dorsally. 16. Valve center showing striae, stigma, dilated proximal raphe ends, and shallow circular depressions. 17. High magnification view of the thickened marginal ridge and areolae with small tooth-like projections. 18. View of the valve mantle and overlapping girdle band with a single row of poroids. 19. Rostrate apices with strongly deflected distal raphe end and porellis of the apical pore field positioned entirely on the valve mantle. 20–21. External view of apices showing apical pole fields with porelli that are comprised of small round holes, differentiated morphologically and physically separated from the striae. Scale bars = 10 μm (Fig 15), 5 μm (Fig. 16), 2 μm (Figs 17–19) and 1 μm (Figs 20–21).