Astasia tortuosa
(Stokes) Popova, 1951
Most likely ID: n.a.
Synonym: Menoidium tortuosum
Sampling location: Simmelried
Phylogenetic tree: Astasia tortuosa
Diagnosis:
- cell strongly elongated and flattened, sometimes C- or S-shaped, metabolic
- cell narrows and tapers to posterior end into rounded tip
- anterior end with neck-like tapering
- length 74–95 µm, width 4.5–9 µm
- mouth opening distinctly truncated transversally
- one flagellum, about a third of body length
- reservoir elongate oval
- nucleus central, oval
- paramylon grains uniform
- periplast with fine striation
I find Astasia tortuosa very often in the mud from Simmelried. The species differs from other species of the genus Astasia in its considerable length of almost 100 µm and the shapes of the metabolic movement, which often take a C- or S-shape. In addition to that the anterior end is tapered in a neck-like manner. The paramylon grains are mostly in the frontal half and are about the same size.
Fig. 1 a-f: Astasia tortuosa. L = 98 µm. Different stages of metabolic movement of a specimen. F = flagellum, Nu = nucleus, PG = paramylon grains, Re = reservoir. Obj. 100 X.
Fig. 2 a-c: Astasia tortuosa. L = 93 µm. Different stages of metabolic movement of a second specimen. Obj. 100 X.
Fig. 3 a-b: Astasia tortuosa. A strongly squashed specimen. Note the clockwise running striation of the pellicle (SP). Obj. 100 X.