Closterium acerosum
Ehrenberg ex Ralfs, 1848
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Ulmisried, Pillersee Moor (Austria)
Phylogenetic tree: Closterium acerosum
Diagnosis:
- cells long, slender, slightly curved, inner margin almost straight or concave
- length 250-800 µm, width 30-60 µm
- cells taper shortly before apices
- cell wall colorless, yellowish or brownish
- chloroplast with 3–4 longitudinal ridges
- up to18 pyrenoids per semi-cell, slightly irregularly arranged
- cell wall with fine striation, rarely punctate
- cell wall of apices punctate
- terminal vacuoles with large number crystals
So far I have only found Closterium acerosum in Ulmisried and in the Pillersee Moor. This species grows very large and is easy to recognize in the samples. However, Closterium acerosum can be confused with the similar Closterium pritchardianum, which has a very similar shape. However, the cell wall of Closterium pritchardianum shows clear rows of dots and interrupted lines, while the cell wall of Closterium acerosum shows a fine line pattern (s. fig. 2), which only rarely appears slightly dotted. According to my measurements, there are 12-14 lines/10 µm (s fig. 2).
More information and images on Closterium acerosum: Alfred van Geest-Digital image collection of Desmids-Closterium acerosum
Fig. 1 a-b: Closterium acerosum. L = 683 µm. A specimen in DIC (a) and brightfield illumination (b). Obj. 20 X.
Fig. 2: Closterium acerosum. The surface of the cell wall with a fine striation of about 12 lines/10 µm. Obj. 100 X.
Fig. 3 a-b: Closterium acerosum. The apex in DIC (a) and brightfield illumination (b). The terminal vacuole (TV) is filled with a large number of moving crystals. Obj. 100 X.
Fig. 4: Closterium acerosum. The cell wall of the apices are punctate (arrow). Obj. 100 X.