Kützing 1844 Category: Symmetrical biraphid
BASIONYM: Stauroneis amphicephala Kützing 1844
REPORTED AS: Stauroneis anceps (Krammer and Lange-Bertalot 1986) | Stauroneis anceps (Patrick and Reimer 1966) | Stauroneis anceps (Camburn and Charles 2000)
Contributor: Loren Bahls - December 2011
Length Range: 55-82 µm
Width Range: 11.0-16.8 µm
Striae in 10 µm: 18-21
Valves are linear-elliptic-lanceolate with abruptly protracted, rostrate to subcapitate apices. The axial area is narrow and nearly linear, widening a bit near the central area. The central area is shaped like a bow tie and is wider near the valve margins. Shortened striae are occasionally present in the central area. The raphe is moderately lateral. Proximal raphe ends are nearly straight, terminated by small, weakly inflated pores. Striae are radiate throughout. Areolae are variably spaced and number 18-25 in 10 µm.
Note that previous floras (Krammer and Lange-Bertalot 1986, Patrick and Reimer 1966, Camburn and Charles 2000) did not include S. amphicephala, but treated it under a very broad concept of S. anceps.
Basionym: Stauroneis amphicephala
Author: Kützing 1844
Length Range: 60 µm
Width Range: 12-14 µm
Striae in 10 µm:
Bahls, L. (2010). Stauroneis in the Northern Rockies: 50 species of Stauroneis sensu stricto from western Montana, northern Idaho, northeastern Washington and southwestern Alberta, including 16 species described as new. Northwest Diatoms, Volume 4. The Montana Diatom Collection, Helena, 172 pp.
Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 pp.
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. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Van de Vijver, B., Beyens, L. and Lange-Bertalot, H. (2004). The genus Stauroneis in Arctic and Antarctic Regions. Bibliotheca Diatomologica 50, 312 pp.
Stauroneis amphicephala is widely distributed in the Northern Rockies in habitats ranging from small ponds and wetlands to large lakes. pH in these waters ranges from 6.0 to 8.6 and specific conductance ranges from 35 to 140 µS/cm. Van de Vijver et al. (2004) report Stauroneis amphicephala as widely distributed in the Arctic in a variety of standing waters with a pH range of 6.1 to 8.1 and specific conductance values ranging from near 0 to 280 µS/cm. Such conditions are very similar to those recorded in the Northern Rockies.
Cut Bank Pond, Glacier National Park, Montana: home of Stauroneis amphicephala.
Credit/Source: Loren Bahls