FIGURES 27–32 in Achnanthidium petuniabuktianum sp. nov. (Achnanthidiaceae, Bacillariophyta), a new representative of the A. pyrenaicum group from Spitsbergen (Svalbard Archipelago, High Arctic)

FIGURES 27–32. Achnanthidium petuniabuktianum sp. nov. Light and scanning electron micrographs. All pictures taken from the type population (BR-4177). 27–28. SEM external views of an entire rapheless valve. 29. SEM internal view of an entire rapheless valve. 30. SEM detail of an external rapheless valve. 31. SEM detail of an internal rapheless valve. 32. SEM view showing a frustule in girdle view. Scale bars always 10 μm, except Figs 30–31 where scale bar is 1 μm.