Eunotia sudeticiformis Kociolek, You, Stepanek, Lowe & Wang, 2016, sp. nov.

Valves asymmetrical to the apical axis, dorsal margin with a slight constriction in the middle, ventral margin slightly concave to straight, with ends protracted with a distinct separation from the valve indicated on the ventral margin, poles rounded. Length 38–81 μm, breadth 7–10 μm at the center, 9.4–10.3 μm at the widest point. Striae straight and perpendicular to the margins in the center of the valve, becoming arched and angled to the margins at the ends, with intercalated, shortened striae between some of the striae on the dorsal margin. Striae extending across the valve face 8–12/10 μm. Areolae indistinct under LM, 30–40/10 μm. External proximal raphe ends extend slightly onto the valve face and indistinct. 1–2 isolated, larger openings are present near the external distal raphe ends. Areolae are in small depressions externally with occlusions, internally there are slit-like alveoli that extend across the valve face. Pseudosepta present. A single rimportula is present at one apex of a valve, with a large external opening. In girdle view, the frustule is rectangular and cingula have distinct rows of poroids.

Type:— CHINA. Guizhou Province: Maolan Nature Reserve, Karst pond, 25° 17.227’ N, 108° 04.261’ E. Composite sample, J. P. Kociolek & Q. Wang, 4 October 2015 (holotype: COLO! slide and material 10468, Kociolek Collection, University of Colorado, Museum of Natural History Diatom Herbarium, Boulder, USA., here illustrated as Fig. 5, isotype: HANU! slide and material GZ-1510101, Shanghai Normal University, Biology Department Diatom Herbarium, Shanghai, China).

Remarks:— There appear to be two morphotypes present in this population of E. sudeticiformis. One morphotype is slightly more narrow (Figs 10–18) than the other (Figs 1–9). In addition, the narrower morphotype has internal striae are only partially in troughs (Figs 31–34); otherwise they are uni- to biseriate. On the external dorsal margin, some specimens have short spines scattered along the length and shortened striae are much rarer between the striae of regular length (Figs 28–30). Further research is needed to determine if the two morphotypes should be formally recognized as separate taxa.

This new species differs from E. sudetica O. Müller (1898: 12) by the more robust valves and blunter apices. Lange-Bertalot et al. (2011) illustrate two different morphologies for E. sudetica, one from southwest Germany (plate 48, figs 1–13) and another from Italy, Spain and Portugal (plate 48, figs 14–28). It seems unlikely that the morphology from Germany, which is much more narrow, especially at the apices, and either lacking intercalated striae or having them restricted to the dorsal part and not extending onto the valve face, can be the same as the second morphology from Italy, Spain and Portugal. Our specimens are similar in appearance to those of the second morphology, especially when compared with SEM.