Eunotia superbidens

Lange-Bert. 2011      Category: Eunotioid

REPORTED AS: Eunotia praerupta var. bidens (Krammer and Lange-Bertalot 1991, p. 187, Fig. 148: 11-12) 

Eunotia sudetica


Eunotia tauntoniensis

LM scalebar = 10 µm = 40 pixels.


Contributor: David R.L. Burge | Mark Edlund - June 2015
Length Range: 23-111 µm
Width Range: at the valve center: 11.4-16.7 µm
Striae in 10 µm: 7-11 in the valve center, 12-14 at the ends.


Valves are weakly arcuate. The dorsal margins have two broadly rounded undulations. In larger specimens, apices are capitate and obtusely rounded. In smaller specimens, apices are subcapitate. The ends are 6.3-10.2 µm wide. Helictoglossae are visible on the ventral margin, at the apices. Small undulations are present on the ventral side. The raphe curves onto the ventral mantle toward the center valve, with proximal raphe ends positioned at the small ventral undulations. Transapical striae are nearly parallel, becoming curved near the ends. Shortened striae may be present in some specimens, near the dorsal margin. A narrow sternum is present near the ventral margin, near the apices. Areolae are fine and number 26-30 in 10 µm.

In North American specimens, the areolae are less dense than those documented in the original description (30-32 in 10 µm).

Original Description

Author: Lange-Bert. 2011
Length Range: 43-90 µm
Width Range: 14-19 µm
Striae in 10 µm: 7-11

Original Description

Original Images

Cite This Page:
Burge, D., and Edlund, M. (2015). Eunotia superbidens. In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Eunotia superbidens

Contributor: David R.L. Burge | Mark Edlund

Reviewer: Paula Furey


Burge, D.R.L. (2014). Relations of water quality, land use buffers, and diatom communities of connected depressions within the Cache River Watershed, Arkansas, USA. M.S. Thesis. Arkansas State University, Jonesboro, Arkansas. 141 pp.

Lange-Bertalot, H., Bak, M., Witkowski, A. and Tagliaventi, N. (2011). Eunotia and some related genera. Diatoms of the European Inland Waters and Comparable Habitats. 6: 747 pp.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)

NADED ID: 33437

Autecology Discussion

Due to the recent designation as a species by Lange-Bertalot (2011) and it’s likely miss identification as E. praerupta var. bidens and E. bidens, the geographical distribution and ecological niche of E. superbidens is not yet well understood.

Burge (2014) found E. superbidens occurring in less than 30% relative abundance among the epiphyton and benthos of cypress-tupelo wetlands with: 22.2–27.4 C, 5.6–7.4 pH, specific conductivity 71.2–834.0 µS/cm, 8.1–321.0 NTU, DO 0.1–7.7 mg/L, NO3-N 0.01–0.3 mg/L, NO2-N <0.001– 0.1 mg/L, orthophosphate 0.02–2.08 mg/L, and TP 0.11–3.93 mg/L. Other common species were Eunotia bidens, E. bilunaris, E. formica, and E. metamonodon as well as species of Gomphonema, Navicula, Nitzschia, and Pinnularia.