FIGURES 50–55 in Revision of Navicula striolata (Grunow) Lange-Bertalot and N. rumaniensis Hustedt with the description of N. friedelhinziae sp. nov.

FIGURES 50–55. Navicula friedelhinziae Wojtal, Ognjanova-Rumenova, Buczkó & Van de Vijver, sp. nov., SEM, internal images. 51. Details of a central area—raphe slit narrow and straight, running on a thickened, raised sternum. 52, 53. Raphe ends slightly expanded and unilaterally bent and one large poroid located over the helictoglossa. 54, 55. Two apices with corroded poroids showing their ultrastructure. Scale bars: 50 = 10 μm; 51, 52 = 4 μm; 53–55 = 1 μm.