Closterium praelongum Brébisson, 1856
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Mindelsee, Simmelried
Phylogenetic tree: Closterium praelongum
Diagnosis:
- cell long, slender, near apices slightly curved, middle almost straight
- apices slightly bent backwards
- length 380–950 µm, width 25–40 µm
- two chloroplasts, each with 3–5 longitudinal ridges
- 7–25 pyrenoids per cell
- girdle bands absent, sometime pseudogirdle bands
- cell wall smooth or with fine striation
- near apices striation change to punctate
- apices without porus
So far I have only found Closterium praelongung in the shore area of the Mindelsee and in the Simmelried. In both locations, however, Closterium praelongung is not very common.
Closterium praelongum is a very large species within the genus and is usually around 500 µm long. The cells are very slender and only curved at the cell ends. The middle part is parallel-sided and straight. The apices are characteristically slightly bent backwards. I was able to recognize a delicate and narrow striation on the cell wall, which was sometimes interrupted (s. fig. 3). At the apices this delicate striation turns into a punctation, which is typical for the species (s. fig. 4). In each half cell there are very many pyrenoids, which are all arranged along the longitudinal midline (s. fig. 1 a).
Fig. 1 a-b: Closterium praelongum. L = 570 µm. Two focal planes of a specimen found in the Simmelried. Obj. 40 X.
Fig. 2: Closterium praelongum. The apices are slightly curved backwards. A terminal porus is absent. Obj. 100 X.
Fig. 3: Closterium praelongum. The delicate striation of the cell wall. Sometimes the stripes are interrupted. Obj. 100 X.
Fig. 4: Closterium praelongum. Near the apices the striation change to punctate. Obj. 100 X.
Fig. 5: Closterium praelongum. The nucleus (Nu) and the pyrenoids (PY) in a slightly squashed specimen. Obj. 100 X.