(Grunow) Round and Mann 1981 Category: Symmetrical biraphid
BASIONYM: Navicula zellensis Grunow 1860
REPORTED AS: Anomoeoneis zellensis (Patrick and Reimer 1966, p. 381, plate 33, fig. 14) | Anomoeoneis brachysira var. zellensis (Camburn and Charles 2000, p. 22, plate 17, figs 46-48)
Contributor: Loren Bahls - March 2014
Length Range: 17-25 µm
Width Range: 4.0-5.2 µm
Striae in 10 µm: 30-32
Valves are linear with parallel sides and bluntly rounded, subrostrate apices. The axial area is narrow. The central area is moderately large and rhombic to elliptic. The raphe is straight. Proximal raphe ends are straight. Distal raphe ends are T-shaped. Striae are weakly radiate. Areolae are transapically elongate. Areolae are transapically elongate and irregularly spaced, creating an undulating longitudinal line on each side of the raphe.
The population shown here does not include larger valves that are typically triundulate with convex margins.
Basionym: Navicula zellensis
Author: Grunow 1860
Length Range: µm
Striae in 10 µm:
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.
Grunow, A. (1860). Uber neue oder ungenügend gekannte Algen. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wein, 10: 503-582.
Lange-Bertalot, H. and Moser, G. (1994). Brachysira Monographie der Gattung. Bibliotheca Diatomologica 29: 1-212.
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.
Round, F.E. and Mann, D.G. (1981). The diatom genus Brachysira. I. Typification and separation from Anomoeneis. Archiv Protistenkunde 124: 221-231.
The specimens pictured on this website are from Big Therriault Lake in northwest Montana (photo below). Big Therriault Lake has a pH of 9.05 and s specific conductance of 176 µS/cm. Camburn & Charles (2000) reported B. zellensis from low-alkalinity lakes in New York. Lange-Bertalot & Moser (1994) report this species from temperate and cold regions of the Northern Hemisphere in circumneutral waters with low to moderate electrolyte content.
Big Therriault Lake, Ten Lakes Scenic Area, Kootenai National Forest, Montana: home of Brachysira zellensis.
Credit/Source: Loren Bahls