Astasia cylindrica (Fromental, 1874)
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Astasia cylindrica
Diagnosis:
- body variable from cylindrical to club-shaped, not or weakly bent, not flattened
- in cylindrical form posterior and anterior end rounded, sides parallel
- length 16–20 µm (of elongated cell)
- one flagellum, almost of body length
- distinct striation that spirals counterclockwise
- paramylon bodies elongate roundish to short rod-shaped
I found Astasia cylindrica in Simmelried in February 2017. During metabolic movement, this species adopt cylindrical shapes with almost parallel sides and rounded ends. This distinguishes it from all other Astasia species. Additional characteristics are the small size of about 20 µm, the distinct striation and the flagellum that is not quite body long. The paramylon granules were described by Pringsheim (1942) as “länglich rundlich bis kurz stabförmig (elongate roundish to short rod-shaped)”. In my population the paramylon grains were round or broadly oval.
Fig. 1 a-e: Astasia cylindrica. L = 16–19 µm. Different stages of the metabolic movement of a freely swimming specimen. Note the the cylindrical forms (b and c) during the metabilic movement and the distinct striation of the pellicle spirals counterclockwise (e). Obj. 100 X.