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Halamphora thumensis

(A.Mayer) Levkov 2009      Category: Asymmetrical biraphid
BASIONYM: Amphora coffeaeformis var. thumensis Mayer 1919
SYNONYM(S): Amphora thumensis (Mayer) Krieger 1929 | Cymbella thumensis (Mayer) Hust. 1945 

Halamphora oligotraphenta


Halamphora veneta

LM scalebar = 10 µm = 80 pixels.


Contributor: Joshua Stepanek - March 2011
Length Range: 9-13 µm
Width Range: 3.8-4.2 µm
Striae in 10 µm: 22-25


Valves are broadly semi-elliptical to semi-circular, with a smoothly arched dorsal margins and convex ventral margins. Valve ends are protracted and capitate. The raphe is located near the ventral margin, straight, with proximal ends straight to slightly dorsally deflected. The axial area is narrow at the poles, widening to form a lanceolate central area. A dorsal fascia is absent. A ventral fascia is present, extending to the ventral margin. Dorsal striae are composed of a single row of areolae, parallel near the central area becoming radiate towards the poles. Ventral striae are radiate near the central area, becoming slightly convergent near the poles.

The systematic position of Halamphora thumensis was under some debate. See Kingston et al. (1980), Krammer (1980) and Levkov (2009) for a thorough discussion.

Original Description

Basionym: Amphora coffeaeformis var. thumensis
Author: Mayer 1919
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Stepanek, J. (2011). Halamphora thumensis. In Diatoms of the United States. Retrieved May 26, 2018, from

Species: Halamphora thumensis

Contributor: Joshua Stepanek

Reviewer: Sam Rushforth


Kingston, J.C., Lowe, R.L. and Stoermer, E.F. (1980). The frustular morphology of Amphora thumensis (Mayer) A.Cl. from northern Lake Michigan and consideration of its systematic position. Trans. Amer. Micros. Soc., 99 (3): 276-283.

Krammer, K. (1980). Morphologic and taxonomic investigations of some freshwater species of the diatom genus Amphora Ehr. Bacillaria 3:197-225.

Levkov, Z. (2009). Amphora sensu lato. In Diatoms of Europe, Volume 5. (H. Lange-Bertalot, ed). A.R.G. Gantner Verlag K.G. 916pp.

Mayer, A. (1919). Bacillariales von Reichenhall und Umgebung. Kryptogamische Forschungen herausgegeben von der Kryptogamenkommission der Bayerischen Botanischen Gesellschaft zur Erforschung der heimischen Flora 1(4):191-216.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Halamphora thumensis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 7005

Autecology Discussion

Reported in small abundances in oligotrophic lakes