(Naegeli) Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Cymbella amphicephala Naegeli ex Kützing 1849
REPORTED AS: Cymbella amphicephala (Patrick and Reimer 1975, plate 4, fig. 11) | Cymbella amphicephala (Krammer and Lange-Bertalot 1986, fig. 142: 3-14) | Cymbella amphicephala (A. Schmidt et al. 1875, fig. 9: 64)
Contributor: Loren Bahls - July 2012
Length Range: 20-32 µm
Width Range: 6.4-8.7 µm
Striae in 10 µm: 12-16 at center valve, up to 18 at the ends
Valves are elliptic and slightly dorsiventral with the curvature of the dorsal and ventral sides very similar. Apices are capitate to subcapitate and bent slightly towards the ventral margin. The axial area is narrow and located near the midline of the valve. The central area is very small and asymmetric, formed by 1-3 short striae on one or both sides. The raphe is filiform with proximal ends deflected slightly towards the ventral margin. Proximal raphe ends are not expanded. Distal raphe ends are deflected dorsally. Striae are slightly radiate throughout and more closely spaced towards the apices. Areolae are difficult to resolve in LM and number 32-35 in 10 µm.
Basionym: Cymbella amphicephala
Author: Naegeli ex Kützing 1849
Length Range: µm
Striae in 10 µm:
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.
Kützing, F.T. (1849). Species Algarum. Lipsiae. F.A. Brockhaus, 922 pp.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Schmidt, A. (-). (1874-1959). Atlas der Diatomaceen-Kunde, von Adolf Schmidt, continued by Martin Schmidt, Friedrich Fricke, Heinrich Heiden, Otto Muller, Friedrich Hustedt. Reprint 1984, Koeltz Scientific Books, Konigstein, 480 plates.
Cymbopleura amphicephala is widely distributed in small headwater lakes and streams throughout the Northwest United States, primarily in mountain regions but also in plains streams. Here it prefers well oxygenated and alkaline (calcium-bicarbonate) waters with moderate electrical conductance (see table below). It is rarely found in abundance. Patrick & Reimer (1975) report it as widespread in the United States “frequently under conditions of high oxygen content and at a pH above 7”. Cymbopleura naviculiformis also prefers well oxygenated waters, but waters with circumneutral pH and much lower concentrations of dissolved solids (Montana Diatom Database).
Abundance-weighted means of selected water quality variables measured concurrently with the collection of samples containing Cymbopleura amphicephala.
Credit/Source: Montana Diatom Database
When first opened, the page for Cymbopleura amphicephala on this website was presented in a broad sense. That is, it included images and measurements for C. amphicephala, C. frequens and C. similiformis. These three taxa are are now considered to be unique biological species. As of this update, the taxonomic circumscription was reduced so that now only images and measurements of C. amphicephala sensu stricto are presented. - S. Spaulding and L. Bahls