FIGURES 13–23. Chaetoceros densus, Chaetoceros eibenii. Figs 13, 14, 16 in The planktonic diatom genus Chaetoceros Ehrenberg (Bacillariophyta) from the Adriatic Sea

FIGURES 13–23. Chaetoceros densus, Chaetoceros eibenii. Figs 13, 14, 16: LM. Figs 15, 20, 21: TEM. Figs 17–19, 22–23: SEM. Figs 13–15: Chaetoceros densus field material. 13) Terminal part of a chain. 14) Sibling valves in valve view. 15) Detail of a seta. Figs 16, 18–22: Chaetoceros eibenii culture material, strain PMFH1. 16) Complete chain of two cells. Fig. 17: Chaetoceros eibenii field material. 17) Terminal part of a chain showing wide hexagonal apertures and a rimoportula visible on every valve. 18) Valve view of sibling valves showing setae divergence. 19) External view of the valve with rimoportula and hyaline rim on the marginal ridge (arrows). 20) Detail of the seta. 21) Detail of a broken seta showing the ornamentation pattern of the side wall. The larger round poroid is indicated by an arrow. 22) Hexagonal cross-section of the seta. 23) Seta tip. Scale bars: 16= 50 μm; 13, 14, 17=10 μm; 18, 19=5 μm; 15, 20–23=1 μm.