Achnanthidium nanum (F. Meister) Novais & Jüttner; 2015; 121
Synonymy
Achnanthes nana Meister 1935
Key references
Novais M.H., Jüttner I., Van de Vijver B., Morais M.M., Hoffmann L., Ector L. 2015. Morphological variability within the Achnanthidium minutissimum species complex (Bacillariophyta): comparison between the type material of Achnanthes minutissima and related taxa, and new freshwater Achnanthidium species from Portugal. Phytotaxa. 224(2): 101-139.
Morphology
Size
4.9-11.5 µm long, 1.7-2.4 µm wide (UK population).
Shape
Valves linear to linear-elliptic with broadly rounded, sometimes subrostrate ends. Frustules in girdle view bent.
Symmetry
Valves isopolar, bilaterally symmetrical.
Valve
Frustules heterovalvar with concave raphe valve and convex rapheless valve.
Striae
Striae slightly radiate, more strongly radiate towards the apices, almost equidistant throughout the valve or slightly denser towards the apices, visible in LM, 28–36 in 10 µm.
Axial area
Narrow linear axial area, slightly widening towards the centre.
Central area
Inconspicuous central area bordered by one more widely spaced stria on both sides, sometimes one of the central stria is absent.
Raphe
Straight and filiform raphe with proximal ends slightly expanded and straight, internally slightly deflected in opposite directions, distal ends straight.
SEM morphology
Striae mainly composed of 3–4 rounded to transapically elongated areolae. Areolae internally covered by hymenes. A single row of elongated or slit-like areolae on the mantle, separated from the striae on the valve face by a hyaline area.
4.9-11.5 µm long, 1.7-2.4 µm wide (UK population).
Shape
Valves linear to linear-elliptic with broadly rounded, sometimes subrostrate ends. Frustules in girdle view bent.
Symmetry
Valves isopolar, bilaterally symmetrical.
Valve
Frustules heterovalvar with concave raphe valve and convex rapheless valve.
Striae
Striae slightly radiate, more strongly radiate towards the apices, almost equidistant throughout the valve or slightly denser towards the apices, visible in LM, 28–36 in 10 µm.
Axial area
Narrow linear axial area, slightly widening towards the centre.
Central area
Inconspicuous central area bordered by one more widely spaced stria on both sides, sometimes one of the central stria is absent.
Raphe
Straight and filiform raphe with proximal ends slightly expanded and straight, internally slightly deflected in opposite directions, distal ends straight.
SEM morphology
Striae mainly composed of 3–4 rounded to transapically elongated areolae. Areolae internally covered by hymenes. A single row of elongated or slit-like areolae on the mantle, separated from the striae on the valve face by a hyaline area.
Literature
References are given in chronological order.
Reference |
Citation |
|---|---|
| Meister F. 1935. Seltene und neue Kieselalgen. 44. Berichte der Schweizer Botanischen Gesellschaft. 87-108 pp | Description; Morphology; Type Illustration |
| Novais M.H., Jüttner I., Van de Vijver B., Morais M.M., Hoffmann L., Ector L. 2015. Morphological variability within the Achnanthidium minutissimum species complex (Bacillariophyta): comparison between the type material of Achnanthes minutissima and related taxa, and new freshwater Achnanthidium species from Portugal. Phytotaxa. 224(2): 101-139. | Morphology; Ecology; Taxonomy; Type Illustration; Illustrations; |
Similar Species
Similar species not published on this website:
Achnanthidium hoffmannii Van de Vijver; 2011; 195/196
Achnanthidium pseudolineare Van der Vijver, Novais & Ector; 2011; 186
This page should be cited as:
Jüttner I. Achnanthidium nanum (F. Meister) Novais & Jüttner; 2015; 121. In: Jüttner I., Carter C., Cox E.J., Ector L., Jones V., Kelly M.G., Kennedy B., Mann D.G., Turner J. A., Van de Vijver B., Wetzel C.E., Williams D.M..
Freshwater Diatom Flora of Britain and Ireland. Amgueddfa Cymru - National Museum Wales. Available online at https://naturalhistory.museumwales.ac.uk/diatoms/browsespecies.php?-recid=4297. [Accessed:
].
Image Gallery
Record last modified: 27/12/2020