Euglena intermedia
(Klebs) Schmitz, 1884
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Euglena intermedia
Diagnosis:
- cell elongated cylindrically with almost parallel sides
- posterior end tapered to short point
- anterior end blunt
- length 94–145 µm
- euglenoid movement
- flagellum short, one-sixth to one-third of body length
- numerous chloroplasts, disc-shaped, pyrenoids absent
- large paramylon grains, oblong shaped
- pellicle faintly striated
- nucleus central
- eyespot red, conspicuous
So far I have only been able to find Euglena intermedia in the Simmelried. The species stands out due to its elongated, cylindrical shape with a short posterior tip. However, a reliable classification can only be made by closely examining the chloroplasts. In Euglena intermedia they are disc-shaped and have no pyrenoid (s. fig. 4 b). This distinguishes it from the similar species Euglena deses, which has an almost identical body shape and also disc-shaped chloroplasts. However, the chloroplasts of Euglena deses all have a central pyrenoid.
In my population of Euglena intermedia, I have observed deviations in body length from the descriptions of earlier authors. All the specimens I observed were larger than 150 µm. Some specimens even had a length of 180 µm. This means that they were about 20 % larger than described in the literature. As the size specifications for Euglena intermedia also vary between authors, this deviation is perhaps within the natural variance. All other characteristics correspond to the descriptions in the literature.
Fig. 1 a-f: Euglena intermedia. L = 179 µm. Different phases of the euglenoid movement. Obj. 40 X.
Fig. 2 a-b: Euglena intermedia. L = 158 µm. Two focal planes of a slightly squashed specimen. Note the pointed posterior end (PE). The flagellum (F) of this specimen has a length of about 50–60 µm. Obj. 40 X.
Fig. 3 a-c: Euglena intermedia. L = 162 µm. A slightly squashed specimen in detail. The flagellum was already shed off. ES = eyespot, RE = reservoir. Obj. 100 X.
Fig. 4 a-c: Euglena intermedia. Three focal planes on the faint striation of the pellicle (SP), the disc-shaped chloroplasts (Chl) without pyrenoid and the oblong shaped paramylon grains (PG). Nu = nucleus, RE = Reservoir. Obj. 100 X.