Micrasterias jenneri Ralfs, 1848
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Schwemm Moor (Austria)
Phylogenetic tree: Micrasterias jenneri
Diagnosis:
- body rounded, almost rectangular
- length 150–180 µm, width 100–130 µm
- linear deep sinus
- semi-cells 5 lobed
- incisions of lobes are moderately deep
- polar lobe convex with notch-shaped incision
- cell surface with fine pores
I have only found Micrasterias jenneri once before in 2004 in the Schwemm Moor in Austria. The Schwemm Moor is located near the Walchsee. The find is interesting because Lenzenweger (1996) writes: “from Austria there is so far only a single, rather dubious record from a waterhole on the Tauernhöhe at 1700m (Bock, 1960)”. It may therefore be a lucky chance find of this rare desmid alga.
The shape of Micrasteria jenneri is somewhat reminiscent of Micrasterias denticulata. However, the latter species is considerably larger, is slightly waisted and above all has more lobes, which are cut twice by incisions. In Micrasterias jenneri, each lobe is only moderately incised once. The shape is therefore much simpler.
The few specimens I found were between 150–160 µm long. All specimens were densely filled with starch grains, making the pyrenoids unrecognizable.
Fig. 1 a-b: Micrasterias jenneri. L = 152 µm. Two focal planes of a specimen found in the Schwemm Moor 2004. Obj. 40 X.
Fig. 2: Micrasterias jenneri. A part of the specimen as shown in fig. 1 a-b in detail. Obj. 100 X.
Fig. 3: Micrasterias jenneri. A specimen in darkfield illumination. Obj. 40 X.