FIGURES 18–22 in Further studies on the species diversity of the marine planktonic diatom genus Skeletonema (Bacillariophyta) in the Mexican Pacific

FIGURES 18–22. Skeletonema pseudocostatum, LM (18) and SEM (19–22). Fig. 18. A complete chain with 9 cells, one cell is dividing (arrow). Fig. 19. Broken chain with 4 cells in development. Fig. 20. Terminal part of a chain, with fusion of the IF's, including 1:1 and 1:2 junctions. Fig. 21. Two terminal valves with relative high valve mantle and TF's showing the characteristic spines of their tips (small arrows) and a TR (arrow). Fig. 22. A terminal valve showing the areolae on the face, TF's and TR (arrow).