Astasia tortuosa

(A. C. Stokes) T. G Popova

Most likely ID: n.a.


Synonym: Menoidium tortuosa


Sampling location: Simmelried


Phylogenetic tree: Astasia tortuosa



  • cell long elongated and flattened, sometimes C- or S-shaped, metabol
  • cell narrows and tapers to posterior end into rounded tip
  • anterior end with neck-like taper
  • length 74–95 µm, width 4.5–9 µm
  • distinctly transversely truncated mouth opening
  • one flagellum, about a third of body length
  • reservoir elongate oval
  • nucleus central, oval
  • paramylon grains uniform
  • periplast with fine striation
Astasia tortuosa

I find Astasia tortuosa very often in the mud from Simmelried. The species differs from other species of the genus Astasia by its considerable length of almost 100 µm and the shapes of the metabolic movement, which often take a C- or S-shape. To that the anterior end is tapered neck-like. The paramylon grains are mostly in the front 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.