Nitzschia vitrea Norman

GRAEFF, C. L., KOCIOLEK, J. P. & RUSHFORTH, S. R., 2013, New and Interesting Diatoms (Bacillariophyta) from Blue Lake Warm Springs, Tooele County, Utah, Phytotaxa 153 (1), pp. 1-38 : 28-30

publication ID

https://doi.org/ 10.11646/phytotaxa.153.1.1

DOI

https://doi.org/10.5281/zenodo.5100708

persistent identifier

https://treatment.plazi.org/id/546B8784-F975-3972-FF3D-7F0BFEEF6649

treatment provided by

Felipe

scientific name

Nitzschia vitrea Norman
status

 

Nitzschia vitrea Norman (1861: 7, pl. 2, fig. 4) ( Figs 138–154 View FIGURES 138–144 View FIGURES 145–150 View FIGURES 151–154 )

Valves lanceolate, tapering to blunt asymmetrically-rounded apices. Length 42.0–195.0 µm, breadth 7.5–12.0 µm. Raphe eccentric with distinctly elevated keel. Fibulae distinct and variably spaced, with no central nodule evident ( Figs 140, 143 View FIGURES 138–144 ). Fibulae number 4–6/ 10 µm. Striae distinctly punctate, and the striae may have some areolae missing giving the sense of longitudinal undulations in the striae ( Figs 138, 142 View FIGURES 138–144 ). Striae number 23–27/ 10 µm. Areolae number within a stria is highly variable, due to the nature of the areolae, 10–30/ 10 µm. Striae appear to stop before the margin on the side opposite the keel where there is a longitudinal hyaline strip ( Figs 138–139, 142 View FIGURES 138–144 ).

In the SEM the longitudinal hyaline strip opposite the keel is apparent ( Figs. 146, 148 View FIGURES 145–150 ) and appears to be part of the valve mantle. There is an organized, nearly continuous row of areolae adjacent to the raphe ( Figs 148–150 View FIGURES 145–150 ). The raphe is continuous at the valve center and much of the keel is unornamented ( Figs 145–150 View FIGURES 145–150 ). Externally, the areolae are generally oval ( Figs 147–150 View FIGURES 145–150 ) but they narrow on the inside of the valve ( Fig. 150 View FIGURES 145–150 ) to become more elongate ( Figs 153–154 View FIGURES 151–154 ). The striae are interrupted at the robust fibulae ( Figs 153–154 View FIGURES 151–154 ) and then continue across roughly ⅔ of the valve mantle adjacent to the fibulae ( Fig. 152 View FIGURES 151–154 ). Internally at the apex, a small helictoglossa is present.

Distribution:— Nitzschia vitrea was found rarely in samples from the main basin of Blue Lake and the surrounding marshes. It is most common in the marsh to the south of Blue Lake (COLO 8529).

Observations:—This species is part of the Lineares subgroup within the genus Nitzschia Hassall (Krammer & Lange-Bertalot 1988, Hustedt 1930). Mann (1980: figs 18–19) previously published two SEM images of this taxon, showing the steep mantle, many open cingula, and distinct keel, but otherwise SEM images of this species have not previously been published. The openings between the fibulae are quite narrow, making observations of the raphe around the middle of the valve difficult from the interior. The structure of the striae, apparent lack of areola occlusions, and the steep keel of this diatom make it quite distinctive among other members of the genus Nitzschia . The Lineares subgroup seems, from keys to the subgroups of the genus (e.g. Krammer & Lange-Bertalot 1988, Hustedt 1930), to have few distinguishing features. Further research will be necessary to understand if this is a natural group and to better place this subgroup within the Bacillariales .

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