Figure 3

Cyclotella choctawhatcheeana. Lake Alchichica. (a) Whole valve, internal view showing central and marginal fultoportulae (cfp, mfp) and the rimoportula (arrowed) SEM Scale bar = 1 μm (b) Internal view of marginal area showing the fultoportulae (fp) every second or third costa and the rimoportula (rp). SEM. Scale bar = 1 μm (c) Detail of the internal view of the marginal fultoportulae with two satellite pores and a single rimoportula between the fultoportulae. SEM. Scale bar = 0.5 μm (d) Detail of the central area with four fultoportulae showing three satellite pores each. SEM Scale bar = 0.5 μm