Tetracyclus glans

(Ehrenberg) Mills 1935      Category: Araphid
BASIONYM: Navicula? glans Ehrenb. 1838
SYNONYM(S): Odontidium glans (Ehrenb.) Kütz. 

Terpsinoë musica


Tetracyclus hinziae

LM scalebar = 10 µm = 40 pixels.


Contributor: Ian Bishop - August 2014
Length Range: 19-38 µm
Width Range: 13-21 µm
Striae in 10 µm: 21-23


Valves are elliptic-lanceolate with a large central inflation and rounded to pointed apices. Thick transapical costae are mostly primary and evenly spaced at 2-3 in 10 µm. The striae are faint compared to the costae and are slightly radiate, more so toward the valve margins. Areola density is 21-27 in 10 µm. The axial area is narrow and linear, sometimes with poorly defined margins. Copulae contain septa that extend approximately 1/4 - 1/3 of the length of the valve. The above images were taken from populations from the Pacific Northwest and did not have rimoportulae, but 1-2 have been found on valves from European populations (Williams 1987).

Tetracyclus glans, T. rupestris and T. emarginatus comprise the three extant species within the genus Tetracyclus, which includes a large number of extinct species (Williams, 1987). North American T. glans valves are smaller than those observed in European populations (Williams 1987).

Tetracyclus lacustris is a later synonym for T. glans. Although T. lacustris is commonly used, T. glans is the correct name, by priority. Ehrenberg (1838) described the taxon first (as Navicula? glans). Later, Ralfs (1843) described the same organism as T. lacustris. See Williams (1989) and Williams (1996) for detail.

Original Description

Basionym: Navicula? glans
Author: Ehrenb. 1838
Length Range: 26.4-52.8 µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bishop, I. (2014). Tetracyclus glans. In Diatoms of the United States. Retrieved April 25, 2018, from http://westerndiatoms.colorado.edu/taxa/species/tetracyclus_glans

Species: Tetracyclus glans

Contributor: Ian Bishop

Reviewer: Mark Edlund, David R.L. Burge


Bishop, I.W. and Spaulding, S.A. (2015). Tetracyclus hinziae (Bacillariophyta), a new species from the central Cascade Mountains (WA, USA). Phytotaxa 205(3): 197-204. 10.11646/phytotaxa.205.3.7

Ehrenberg, C.G. (1838). Die Infusionsthierchen als vollkommene Organismen. Ein Blick in das tiefere organische Leben de Natur. erlag von Leopold Voss, Leipzig. pp. 1-xvii, 1-548, pls. 1-64.

Ehrenberg, C.G. (1854). Mikrogeologie. Einundvierzig Tafeln mit über viertausend grossentheils colorirten Figuren, Gezeichnet vom Verfasser. Voss, Leipzig., Pl. 5, II, fig. 23 (iconotype).

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

Mills, F.W. (1935). An index to the genera and species of the Diatomaceae and their synonyms. Wheldon and Wesley, London, Part 21, pp. 1916-1932.

Pritchard, A. (1861). A history of infusoria, living and fossil. Edition IV, Whittaker & Co., London, 968 pp.

Ralfs, J. (1843). On the Diatomaceae. Annals and Magazine of Natural History 12: 104-111, pl. 2.

Williams, D.M. (1987). Observations on the genus Tetracyclus Ralfs (Bacillariophyta) I. Valve and girdle structure of the extant species. British Phycological Journal 22: 383-399. 10.1080/00071618700650451

Williams, D.M. (1989). Observations on the genus Tetracyclus Ralfs (Bacillariophyta) II. Morphology and taxonomy of some fossil species previously classified in Stylobium Ehrenberg. British Phycological Journal 24: 317-327.

Williams, D.M. (1996). Fossil species of the diatom genus Tetracyclus (Bacillariophyta, ‘Ellipticus’ species group): Morphology, interrelationships and the relevance of ontogeny. Philosophical Transactions of the Royal Society of London, B, 351:1 759-1782. 10.1098/rstb.1996.0156

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Tetracyclus glans CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

This taxon has been found throughout the west in cool, oligotrophic waterbodies, particularly growing in moist zones in association with mosses and liverworts (Bishop and Spaulding, 2015).

The specimens here are from the Snoqualmie River in the Central Cascades and from H.E. Sovereign’s collections (California Academy of Sciences) from Lake Ozette, on the Olympic Peninsula, both in Washington state. Tetracyclus glans was found in both locations with other araphid taxa, including Tabellaria flocculosa, Odontidium mesodon, Odontidium hyemale, and Meridion circulare. Tetracyclus glans also co-occurred in the Cascade samples with a new species of Tetracyclus.

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

Tetracyclus glans

EMAP Response Plots

Tetracyclus glans

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.