(Ehrenberg) Mann 1989 Category: Symmetrical biraphid
BASIONYM: Navicula americana Ehrenberg 1843
REPORTED AS: Navicula americana (Patrick and Reimer 1966, p. 493, pl. 47, fig. 3) | Navicula americana (Krammer and Lange-Bertalot 1986, p. 188, fig. 67: 1)
Contributor: Loren Bahls - March 2014
Length Range: 58.3-93.4 µm
Width Range: 14.6-19.1 µm
Striae in 10 µm: 16-18 midway between valve center and apex
Valves are broadly linear, with parallel or weakly concave margins. Apices are obtusely rounded. The axial area is narrow and undulate, bordered on each side by a wide conopeum. The conopea are continuous through the central area, where they expand laterally. The conopea narrow to a point near the apices. The central area is wide and rounded. The central nodule, defined by the inner margins of the conopea, is small and elliptic. The raphe is filiform and follows the undulate margins of adjacent conopea. Proximal raphe ends are deflected slightly to one side and tipped with small pores. Distal raphe ends are comma-shaped. Central striae are straight, parallel, and shorter, but with about the same spacing as more distal striae, which are curved and radiate.
Basionym: Navicula americana
Author: Ehrenberg 1843
Length Range: µm
Striae in 10 µm:
Ehrenberg, C.G. (1843). Verbreitung und Einfluß des mikroskopischen Lebens in Süd- und Nord-Amerika. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin, 1841: 291-445, 4 Tafel.
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.
Mann, D.G. (1989). The diatom genus Sellaphora: Separation from Navicula. British Phycological Journal 24: 1-20.
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.
Specimens of S. americana pictured and described on this web page were collected from a pond in Lincoln County, Montana and from Denton Slough, a backwater bay of Lake Pend Oreille in Bonner County, northern Idaho. The Montana pond has a pH of 6.0 and specific conductance of 50 µS/cm. Denton Slough has a pH of 7.3 and specific conductance of 150 µS/cm. Krammer and Lange-Bertalot (1986) report this species as cosmopolitan in standing waters. Patrick and Reimer (1966) report it as widely distributed in U. S. waters with circumneutral pH.