Closterium dianae var. pseudodianae
(Roy) Krieger, 1935
Most likely ID: n.a.
Synonym: Closterium pseudodianae
Sampling location: Schwemm Moor (Austria)
Phylogenetic tree: Closterium dianae var. pseudodianae
Diagnosis:
- cell crescent-shape, 14–21 times longer than wide
- apices obliquely truncated with a terminal pore
- inner margin sometimes straight in mid-region
- length 150–260 µm, width 14–18 µm
- cell wall smooth without striation
- two chloroplasts, each with 3–5 longitudinal ridges
- several pyrenoids arranged along cell axis
- girdle bands absent
- terminal vacuoles with several crystals
- nucleus central
I found several specimens of Closterium dianae var. pseudodianae in an old sample from the Schwemm Moor. The cells are more slender and curved compared to the basic form Closterium dianae.
To distinguish it from the similar varieties Closterium dianae var. arcuatum and Closterium dianae var. minus, it is necessary to measure the length and width of the cells. Closterium dianae var. arcuatum is significantly longer at over 350 µm, and Closterium dianae var. minus is clearly smaller at under 150 µm in length. In addition, Closterium dianae var. arcuatum is also wider in the middle of the cell at 20–30 µm than Closterium dianae var. pseudodianae.
Closterium dianae var. pseudodianae has so far only been detected in Austria in Lake Neusiedl by Kusel & Fetzmann (1974). In Germany, the species has been found, for example, in the Harz National Park (Reinecke, 2022). In general, the species is considered rare.
Fig. 1 a-b: Closterium dianae var. pseudodianae. L = 242 µm. Two focal planes of a specimen found in the Schwemm Moor. In the middle the cell is 15 µm wide. Obj. 60 X.
Fig. 2 a-b: Closterium dianae var. pseudodianae. L = 242 µm. Focal plane on the nucleus (Nu) and on the smooth cell wall. PY = pyrenoid. Obj. 100 X.
Fig. 3: Closterium dianae var. pseudodianae. The distinct porus (PO) of the apex. Obj. 100 X.