Distigma sennii Pringsheim, 1942
Most likely ID: n.a.
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Synonym: n.a.
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Sampling location: Simmelried
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Phylogenetic tree: Distigma sennii
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Diagnosis:Â
- cell club-shaped, tapering towards posterior end
- anterior end truncated
- often bent, posterior end forms rounded tip
- length 45–68 µm
- long flagellum about two thirds of cell length
- short flagellum about one tenth of cell length
- nucleus central with a central nucleolus
- striation of pellicle fine, hard to see
- euglenoid movement reduced
I found Distigma sennii in August 2010 in the Simmelried. After that I have no further records. But perhaps I have often overlooked the species because the second, short flagellum, which characterizes the genus Distigma, can only be seen at high magnification.
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The classification as Distigma sennii is based on the truncated anterior end, the length of the cells of about 50 µm and the conical body shape with a tapered posterior end. It can therefore not be Distigma proteus. This species is about twice as long and has a pronounced striation of the pellicle. Distigma globiferum is smaller and the mid-body is clearly enlarged due to a very large nucleus. A further alternative would be Distigma elegans. This species is about the same length and also has a truncated anterior end, but is described to have a very strong euglenoid movement.
Fig. 1 a-d: Distigma sennii. L = 47 µm. Different phases of the euglenoid movement of a freely swimming specimen. Note the two flagella of different length (F1, F2) and the truncated anterior end. Nu = nucleus. Obj. 100 X.
Fig. 2 a-d: Distigma sennii. L = 54 µm. A second specimen during euglenoid movement. Obj. 100 X.