Eunotia kociolekii

The dorsal margin is convex and slightly biundulate in larger valves and straight in smaller valves. The ventral margin is nearly straight, or only slightly concave. The apices are attenuated, truncated and apically flattened. The ends are slightly set off by a gradual change in slope of the dorsal margin. Helictoglossae are not visible under the LM. One apical rimoportula, with a prominent external pore, is present at the center of the apex (visible in SEM). Also under SEM, the internal openings of the areolae in E. kociolekii are aligned in a narrow groove. The distal raphe ends are curved and clearly visible in the LM. Striae are radiate. Areolae are 32-36 in 10µm. The cell length to width ratio increases with increases in cell size. Smaller cells have L:W of 2.5-3.5:1, while the largest cells have a L:W of 6-8:1.

Comparison of E. kociolekii to other species deserves further clarification. Eunotia kociolekii differs from the original type of E. diodon Ehrenberg (Ehrenberg 1837) by having smaller, narrower valves that are less strongly biundulate than E. diodon and apices that are more truncated and flattened than E. diodon. Subsequent floras present interpretations other than of the Ehrenberg type. Diatomists after Ehrenberg present E. diodon as relatively large and obtusely biundulate valves, 44 - 55 wide (see description in De Toni 1892; also Kützing 1849). In Schmidt’s Atlas (Hustedt 1911, Taf. 270: Figs 14 – 18), E. diodon includes a broad concept of biundulate morphologies with a range of widths and slopes along the dorsal edge to the apices. Eunotia diodon illustrated in Lange-Bertalot & Metzeltin (1996; Taf. 15: Figs 1-2) and Fig. 14 in Krammer & Lange-Bertalot (1991, Taf. 149) are similar in valve shape to E. kociolekii. Other images of “E. diodon” have a smaller length to width ratio (Lange-Bertalot & Metzeltin 1996; Taf. 15: Figs 1-2).

Eunotia kociolekii is longer than E. satelles Nörpel-Schempp et Lange-Bertalot (Lange-Bertalot & Metzeltin, 1996), but where the valves overlap in the lower size range, E. kociolekii could be confused with E. satelles. However, the smaller valves of E. satelles are wider and more steeply sloped towards the apices than E. kociolekii.