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Eunotia pectinalis

(Kütz.) Rabenh. 1864      Category: Eunotioid
BASIONYM: Himantidium pectinalis Kütz. 1844

Eunotia papilioforma


Eunotia perpusilla

LM scalebar = 10 µm = 40 pixels.


Contributor: David R.L. Burge | Mark Edlund - June 2015
Length Range: 28-85 µm
Width Range: 6.7–9.0 µm
Striae in 10 µm: 8.0–12 in the valve center, 11–16 at the ends.


Valves are weakly arcuate. The dorsal margin is convex and has 3 - 5 undulations. In some (especially smaller) specimens, the dorsal undulations are weakly expressed. The ventral margin often has a central inflation. The apices are rounded and slightly recurved to the dorsal side. Helictiglossae are prominent near the apices. The raphe is apparent in few specimens;, the raphe curves around the apical margin and along the dorsal valve. Transpical striae are distinctly punctate and parallel, becoming radiate at the apices. A small sternum is present, near the ventral margin. Areolae are distinct in LM, 24-26 in 10 µm.

This species is presented in the broader concept of Hoffman et al. (2013), including the variety E. pectinalis var. undulata, because populations included a range of dorsal swelling. Other authors (e.g., Patrick and Reimer 1966, Lange-Bertalot et al. 2011) recognize E. pectinalis and E. pectinalis var. undulata as separate taxa.

Original Description

Basionym: Himantidium pectinalis
Author: Kütz. 1844
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Burge, D., and Edlund, M. (2015). Eunotia pectinalis. In Diatoms of the United States. Retrieved May 20, 2018, from

Species: Eunotia pectinalis

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.

Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 pp.

Fallu, M.-A., Allaire, N. and Peinitz, R. (2000). Freshwater diatoms from northern Québec and Labrador (Canada). Species-environment relationships in lakes of boreal forest, forest-tundra and tundra regions. Bibliotheca Diatomologica 45: 1-200.

Foged, N. (1981). Diatoms in Alaska. Bibliotheca Phycologica, Band 53, J. Cramer, Vaduz, 317 pp.

Furey, P.C., Lowe, R.L. and Johansen, J.R. (2011). Eunotia Ehrenberg (Bacillariophyta) of the Great Smoky Mountains National Park, USA. Bibliotheca Diatomologica 56: 1-134.

Hofmann, G., Lange-Bertalot, H., and Werum, M. (2013). Diatomeen im Süßwasser-Benthos von Mitteleuropa: 2 Corrected Edition. Koeltz Scientific Books, Königstein, 908 pp.

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Rabenhorst, L.G. (1864). Flora Europaea Algarum aquae dulcis et submarinae. Sectio I. Algas diatomaceas complectens, cum figuris generum omnium xylographice impressis. Eduardum Kummerum, Lipsiae 359 pp.

Siver, P.A. and Hamilton, P.B. (2011). Diatoms of North America: The Freshwater Flora of Waterbodies on the Atlantic Coastal Plain. Iconographia Diatomologica 22.

Siver, P.A., Hamilton, P.B., Stachura-Suchoples, K. and Kociolek, J.P. (2005). Diatoms of North America. The Freshwater Flora of Cape Cod. Iconographia Diatomologica 14: 1-463.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA
Original INA

California Academy of Sciences (CAS)

Eunotia pectinalis CAS

NCBI Genbank Taxonomy

Eunotia pectinalis NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 33039

Autecology Discussion

Eunotia pectinalis is a cosmopolitan (Foged 1981, Lange-Betalot et al. 2011) species found to be rare (Camburn et al. 1978, Furey et al. 2011) to common (Siver et al. 2005) in abundance. The species is acidophilic and has been found living in the epiphyton, epidendron, epilithon, and metaphyton of oligotrophic to eutrophic lakes ( Camburn et al. 1978, Siver et al. 2005, Siver and Hamilton 2011), streams (Foged 1981, Fallu et al. 2000, Furey et al. 2011), and wetlands (Burge 2014). Specimens we examined were found living among E. bilunaris, E. formica, and E. metamonodon as well as species of Gomphonema, Navicula, and Pinnlaria in cypress-tupelo wetlands of Arkansas with the following water chemistry: 22.2–27.4 ºC, 5.59–7.37 pH, DO 0.05–7.65 mg/L, Specific conductance 71–834 µS, 8.1–321 NTU, NH3-N 0.08–13.03 mg/L, NO3-N 0.01–0.3 mg/L, NO2-N <0.01–0.5 mg/L, TP 0.1–3.9 mg/L, PO4-P 0.02–2.08 mg/L (Burge 2014).

EMAP Assessment

The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Eunotia pectinalis

EMAP Response Plots

Eunotia pectinalis

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.