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Fragilaria amphicephaloides

Lange-Bert. in Hoffman et al. 2011      Category: Araphid
SYNONYM(S): Synedra amphicephala Kütz. | Fragilaria capucina ssp. amphicephala (Kütz.) Lange-Bert. | Fragilaria amphicephala Ehrenb. 
REPORTED AS: Fragilaria capucina var. amphicephala (Krammer & Lange-Bertalot 1991, p. 125, Pl. 109, Figs. 19, 20) 

Fallacia vitrea


Fragilaria crotonensis

LM scalebar = 10 µm = 80 pixels.


Contributor: David R.L. Burge - November 2015
Length Range: 42-71 µm
Width Range: 2.6-3.9 µm
Striae in 10 µm: 11-13


Valves are linear-lanceolate. The apices are narrowly attenuate, with capitate ends. The central area is variable, from bilaterally expanded to weakly unilaterally expanded. In some specimens, the central area is slightly tumid. Striae may absent from the central area, or ghost striae may be present. Striae are parallel, mostly alternate, occurring 11-12 in 10 µm. Striae are interrupted by a narrow axial area, which widens near the central area. Areolae are fine, and not visible in LM. Spines are absent.

This taxon was originally described by Kützing (1844, pg. 64, Pl. 3, fig. 12) as Synedra amphicephala. Later, it was later transferred to the subspecies Fragilaria capucina ssp. amphicephala (Lange-Bertalot 1993, p. 44). Note that Fragilaria capucina var. amphicephala (Krammer & Lange-Bertalot 1991, p. 125, Pl. 109, Figs. 19, 20) is invalid because the baysionym was properly referenced. Finally, it was elevated to the species rank (Hofmann et al. 2011: p. 256, Pl. 7, figs. 7-10).

Original Description

Author: Lange-Bert. 2011
Length Range: 40-75 µm
Width Range: 2-3 µm
Striae in 10 µm: 10-14

Original Description

Original Images

Cite This Page:
Burge, D. (2015). Fragilaria amphicephaloides. In Diatoms of the United States. Retrieved May 25, 2018, from

Species: Fragilaria amphicephaloides

Contributor: David R.L. Burge

Reviewer: Eduardo A. Morales


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

Hofmann, G., Werum, M. and Lange-Bertalot, H. (2011). Diatomeen im Süßwasser-Benthos von Mitteleuropa. Koeltz Scientific Books, Königstein, 908 pp.

Krammer, K. and Lange-Bertalot, H. (1991). Bacillariophyceae. 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.). Süsswasserflora von Mitteleuropa. 2(3): 1-576. Gustav Fisher Verlag, Stuttgart, Germany.

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

Lange-Bertalot, H. (1993). 85 Neue taxa und uber 100 weitere neu definierte Taxa erganzend zur Subwasserflora von Mittleuropa. Bibliotheca Diatomologica 27, 454 p. Cramer, Berlin, Stuttgart.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)

NADED ID: 34193

Autecology Discussion

The specimens shown here were collected in Idaho. It has been reported as being widely distributed across the US (Patrick and Reimer 1966), as Synedra amphicephala var. amphicephala. In Europe, it has been reported in oligotrophic to mesotrophic lakes of the Alps and foothills of southern Germany, with few occurrences in rivers and the lowlands of northern Germany (Hofmann et al. 2013) .