Lange-Bertalot 1980 Category: Symmetrical biraphid
BASIONYM: Navicula pseudolanceolata Lange-Bertalot 1980
Contributor: Loren Bahls - December 2011
Length Range: 41-59 µm
Width Range: 9.0-11.1 µm
Striae in 10 µm: 9-11
Valves are lanceolate, with acutely pointed apices in smaller specimens and weakly protracted, narrowly rounded apices in larger specimens. The axial area is narrow, widening into a small rhombic central area. The raphe is weakly lateral and essentially straight, with relatively distant and only slightly expanded proximal ends. Striae are irregularly shortened and more widely spaced about the central area, strongly radiate and mostly straight, becoming parallel, but not convergent at the valve apices. Lineolae are coarse and number 24 in 10 µm.
Basionym: Navicula pseudolanceolata
Author: Lange-Bertalot 1980
Length Range: 30-50 µm
Width Range: 7-9.5 µm
Striae in 10 µm: 9.5-11
Valves lanceolate to rhombic-lanceolate, ends gradually narrowed, wedge-shaped, length 30-50 microns, breadth 7-9.5 microns. Raphe weakly lateral, axial area narrow, central area small to moderately larger, slightly rhombic to transversely widened. Striae strongly radiate throughout or parallel at the ends, 9.5-11/10 microns; lineolae appear coarse, c. 24/10 microns.
Lange-Bertalot, H. (1980). Zur taxonomischen Revision einiger ökologisch wichtiger “Navicula lineolatae” Cleve. Die Formenkreise um Naviculae lanceolata, N. viridula, N. cari. Cryptogamie, Algologie 1(1):29-50.
Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.
There are 82 records of Navicula pseudolanceolata in the Montana Diatom Collection, from lakes and streams in mountain regions of the Northwest United States. The species is rarely found in abundance. Specimens pictured here are from Lower Branham Lake in the Tobacco Root Mountains of southwest Montana. At the time of sampling this lake had a pH of 8.74 and specific conductance of 64 µS/cm. Lange-Bertalot (2001) reports N. pseudolanceolata from low conductivity or weakly humic acid and oligotrophic lakes in Europe.
Lower Branham Lake, Madison County, Montana: home of Navicula pseudolanceolata.
Credit/Source: Loren Bahls