Acanthoceras zachariasii

(Brun) Simonsen 1979      Category: Centric
BASIONYM: Attheya zachariasii Brun 1894


Achnanthes coarctata

LM scalebar = 10 µm = 20 pixels.


Contributor: Mark Edlund | David R.L. Burge - July 2017
Diameter: 11.9-23.0 µm
Rows of areolae in 10 µm:


Frustules are lightly silicified and typically lie in girdle view. The pervalvar axis is long, 54-121 µm. Valves have bipolar symmetry and are characterized by two long, horn-like extensions (55-65 µm) on each valve. The girdle bands are open, with each end aligned to form a zig-zag suture. The girdle band density is 2.4-3.3 in 10 µm. Cells produce heavily silicified endogenous resting spores, which may be present within frustules. More often, the resting spores are detected in lake sediment deposits. Resting spores range in length from 14.3-41.0 µm and 5.2-11.5 µm in pervalvar axis. They have a scalloped and convex primary valve and a smooth concave secondary valve (Edlund and Stoermer 1993). Because frustules are so lightly silicified, they are often destroyed by typical processing methods. Cells are best observed by making “burn mounts”.

Original Description

Basionym: Attheya zachariasii
Author: Brun 1894
Diameter: 15-20 µm
Rows of areolae in 10 µm:

Original Description

Original Images

Cite This Page:
Edlund, M., and Burge, D. (2017). Acanthoceras zachariasii. In Diatoms of the United States. Retrieved April 21, 2018, from

Species: Acanthoceras zachariasii

Contributor: Mark Edlund | David R.L. Burge

Reviewer: Sarah Spaulding


Brun, J. (1894). Zwei neue Diatomeen von Ploen. Forschungsberichte aus der Biologischen Station zu Plön 2: 52-56.

Edlund, M.B. and Stoermer, E.F. (1993). Resting spores of the freshwater diatoms Acanthoceras and Urosolenia. Journal of Paleolimnology 9: 55-61.

Simonsen, R. (1979). The diatom system: ideas on phylogeny. Bacillaria 2: 9-71.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA
Original INA

California Academy of Sciences (CAS)

Acanthoceras zachariasii CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Acanthoceras zachariasii is a planktonic, ephemeral species of temperate, eutrophic and moderately alkaline lakes and large rivers (Edlund and Stoermer 1993). It is probably more widely distributed, but it is easily destroyed by processing if harsh preparation techniques are used. The specimens shown here are from a shallow, nutrient-rich habitat (Lazy Lagoon) on West Lake Okoboji, Iowa. It has also been collected in other lakes in the Iowa Great Lakes region, including Spirit Lake and East Lake Okoboji.