Navicula goersii
Bahls 1983 Category: Symmetrical biraphid
BASIONYM: Navicula goersii Bahls 1983
LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Loren Bahls | Eduardo Morales | Marina Potapova - November 2011
Length Range: 8-14 µm
Width Range: 3-4 µm
Striae in 10 µm: 14-18
Description
Frustules are flat, almost always coming to rest in valve view due to shallow mantles (1.5-2.0 µm deep). Valves are broadly lanceolate with subrostrate ends in all but the smallest specimens. The axial area is narrow. Central area is broad, rectangular and reaches nearly to the valve margins. A single, shortened stria is present on each side. External raphe fissures are straight and threadlike. Proximal raphe ends are slightly inflated and relatively distant from one another. Terminal raphe fissures are bent diagonally toward the valve margin and are characteristically in close contact with a single areola at each apex, making the raphe fissures appear as hook-like terminations. Striae are broad, lineate, radiate and slightly curved about the central area. The striae extend onto the valve mantle. A crown of small areolae of different shapes are present at each valve apex. Striae are parallel or slightly convergent toward the valve apices.
Original Description
Basionym: Navicula goersii
Author: Bahls 1983
Length Range: 8-14 µm
Width Range: 3-4 µm
Striae in 10 µm: 14-16
Original Description
Valvae late lanceolatae, apicibus angustatis usque ad rostellatos. Area axialis angustata. Area centralis latus, rectangularis, extensus fere ad marginem valvarum, unus abbreviatus stria in uterque latus. Raphe rectus, filiformis. Striae latae, lineolatae, radiatae et leviter curvae circa area centralis, parallelae vel leviter connivens ad apices, 14 (medium) ad 16 (apices) in 10 µm. Longitudo, 8-14 µm (typice 12 µm). Latitudo, 3-4 µm (typice 3.5 µm).
Original Images
Cite This Page:
Bahls, L., Morales, E., and Potapova, M. (2011). Navicula goersii. In Diatoms of the United States. Retrieved May 22, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_goersii
Species: Navicula goersii
Contributor: Loren Bahls | Eduardo Morales | Marina Potapova
Reviewer: Rex Lowe
Image Credit: Loren Bahls, Marina Potapova
- Valves small
- Single short stria on each side of central area
- Apices subrostrate
- Striae radiate, slightly curved about central area
Valves are small (< 20 µm) and broadly lanceolate, with narrow, subrostrate apices. The central area is rectangular with a single, short stria on each side. The striae are slightly radiate and those near the central area are curved.
Compare
Species of Hippodonta have more strongly silicified frustules, broader profiles in girdle view, and simpler external raphe systems that lack the hooked or strongly deflected terminal fissures characteristic of Navicula species. Navicula goersii is distinguished from N. perminuta by its subrostrate rather than obtusely rounded ends. It differs from N. exilis by its smaller size, coarser striation, and rectangular shape of the central area. It differs from N. veneta by its smaller size, subrostrate ends, and distinctly transverse central area. Compared to N. nanissima, N. goersii has coarser striation, a larger central area, broader ends, and a less abrupt transition from radiate to parallel striae toward the apices.
Navicula veneta
Hippodonta
Lange-Bertalot, Witkowski & Metzeltin
Navicula perminuta
Grunow
Navicula exilis
Kützing
Navicula nanissima
(Manguin) Metzeltin & Lange-Bertalot
Citations
Bahls, L.L. (1983). A new diatom from southeastern Montana. Proceedings of the Montana Academy of Sciences 42: 1-6.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 93175
Autecology Discussion
Most records of Navicula goersii are from streams in the semi-arid West and only a few are from the eastern United States. Navicula goersii prefers nutrient-rich alkaline waters with somewhat elevated conductance (see table below). These waters are typical of the sagebrush and grassland prairies of the western United States. Common diatom associates of N. goersii are Diploneis puella, Navicula caterva, Biremis circumtexta, Navicula canalis, Fallacia tenera, Nitzschia reversa, and Pleurosigma delicatulum.
Images
Abundance-weighted means of selected water quality variables measured concurrently with the collection of samples containing *Navicula goersii".
Credit/Source: Montana Diatom Database