Published as part of Sterrenburg, Frithjof A. S., Haan, Myriam De, Herwig, Wulf E. & Hargraves, Paul E., 2014, Typification and taxonomy of Gyrosigma tenuissimum (W. Sm.) J.W. Griffith & Henfr., comparison with Gyrosigma coelophilum N. Okamoto & Nagumo and description of two new taxa: Gyrosigma tenuissimum var. gundulae var. nov. and Gyrosigma baculum sp. nov. (Pleurosigmataceae, Bacillariophyta), pp. 71-80 in Phytotaxa 172 (2) on page 75, DOI: 10.11646/phytotaxa.172.2.2, http://zenodo.org/record/5142351

FIGURES 16–23. Gyrosigma tenuissimum, additional populations, SEM images. Fig. 16. general view, internal. Bar = 20 µm. Fig. 17. Apex, internal. Bar = 4 µm. Fig. 18. centre, internal. Bar = 4µm. Fig. 19. apex, internal. Bar = 4 µm. Fig. 20. general view, external. Bar = 20 µm. Fig. 21. apex, external. Arrow marks apical pore. Bar = 3 µm. Fig. 22. centre, external. Bar = 3 µm. Inset: detail (2x enlargement) showing raphe fissure ends. Fig. 23. apex, external. Arrow marks apical pore. Bar = 3 µm.