Eunotia sudeticiformis, Kociolek & You & Stepanek & Lowe & Wang, 2016

Kociolek, J. P., You, Q-M., Stepanek, J., Lowe, R. L. & Wang, Q-X., 2016, A new Eunotia (Bacillariophyta: Eunotiales) species from Karst formations of southern China, Phytotaxa 265 (3), pp. 285-293 : 288-289

Eunotia sudeticiformis 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.

Figures

FIGURES 1–18. Eunotia sudeticiformis sp. nov. LM. Valve view, size diminution series. 1–9. Wider morphotype. 5. Holotype. 10–18. More narrow morphotype. Scale bar = 10 μm.

FIGURES 31–34. Eunotia sudeticiformis sp. nov. Narrow morphotype. SEM, internal views. 31. Whole valve view showing striae in trough–like openings in the center, but with individual areolae at the dorsal and ventral margins. Scale bar = 1 μm. 32, 33. Center of the valve showing areolae in one (Fig. 32) or two rows (Fig. 33) at the dorsal and ventral portions of the valve as well as in trough-like lines in the center. Scale bars = 1 μm. 34. Valve apex with helictoglossae and large rimportulae evident. Small spines can be seen on the exterior of the dorsal edge of the valve. Pseudoseptum is small at the apex. Scale bar = 1 μm.

FIGURES 28–30. Eunotia sudeticiformis sp. nov. Narrow morphotype. SEM, external views. 28. Whole valve showing striae in shallow troughs, distal raphe ends curved onto the valve face near the apex and small spines scattered along the dorsal margin. Scale bar = 1 μm. 29. Close up of valve center with each areola with a thickened rim that occludes the opening (compare with the few areolae without occlusions).Note that there are few short striae intercalated between the full-length striae on the dorsal margin. Scale bar = 1 μm. 30. Valve apex with distal raphe end barely curving onto the valve face. A few larger areolae are positioned near the raphe opening. The apex on the valve face is unornamented. On the mantle the rimoportula opening is evident. Scale bar = 1 μm.