(Rabenhorst) Krammer 1997 Category: Asymmetrical biraphid
BASIONYM: Navicula cesatii Rabenhorst 1853
REPORTED AS: Cymbella cesatii (Krammer and Lange-Bertalot 1986, p. 325 [in part], pl. 134, figs. 11, 12) | Cymbella cesatii (Patrick and Reimer 1975, p. 21 [in part], pl. 3, fig. 2)
Contributor: Loren Bahls - May 2013
Length Range: 22.0-38.8 µm
Width Range: 4.6-6.0 µm
Striae in 10 µm: 16-19 at the valve center, 21-22 near the apices
Valves are narrowly lanceolate and nearly symmetric with respect to the apical axis. Apices are subrostrate and deflected weakly toward the ventral side. The axial area is narrow. The central area is small and asymmetric, formed by 1-3 shortened striae on the ventral side. The raphe is weakly lateral. Proximal raphe ends are deflected toward the dorsal side. Terminal raphe ends are hooked toward the ventral side. Striae are radiate throughout. Areolae are very fine and difficult to resolve in LM.
The morphological range of E. cesatii presented follows the lectotype designated by Krammer (1997, p. 152, Tafel 182, figs. 1-9) and illustrated below. Note that both Krammer and Lange-Bertalot (1986) and Patrick and Reimer illustrate a broader range of varieties and species within E. cesatii (for example, E. stafsholtii and varities of E. cesatii) in their publications.
Basionym: Navicula cesatii
Author: Rabenhorst 1853
Length Range: 20-41 µm
Width Range: 5.4-6.0 µm
Striae in 10 µm: 18-19
Bahls, L. (2013). Encyonopsis from western North America: 31 species from Alberta, Idaho, Montana, Oregon, South Dakota, and Washington, including 17 species described as new. Northwest Diatoms, Volume 5. The Montana Diatom Collection, Helena, 46 pp.
Krammer, K. (1997). Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema part., Encyonopsis and Cymbellopsis. Bibliotheca Diatomologica 37:1-469.
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.
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.
Rabenhorst, L. (1853). Die Süßwasser-Diatomaceen (Bacillarien) für Freunde der Mikroskopie. Leipzig, 72 pp.
Encyonopsis cesatii is common in small headwater lakes, ponds and springs in the northern Rocky Mountains, where it is often found among mosses. Here it prefers cold, circumneutral waters with low concentrations of nutrients and dissolved solids. In these habitats it is often found in association with Encyonopsis falaisensis. Patrick & Reimer (1975) report it from the New England states and the Great Lakes states. Krammer & Lange-Bertalot (1986) report it as a northern-alpine species and common in the Alps and Finland.
Kootenai Pond, Glacier National Park, Montana: home of Encyonopsis cesatii and Encyonopsis falaisensis.
Credit/Source: Loren Bahls