Vannella simplex, arrow indicates direction

 

 

Vannella simplex (Wohlfarth-Bottermann, 1960) Bovee, 1965

 

Diagnosis: Locomotive form semicircular or fan-shaped, often with long €˜tail€™. Frontal hyaloplasm occupies about half of the cell; the front edge may be smooth or slightly wavy. Rapidly moving cells often have a long €˜tail€™; in cultures and moist-chamber-preparations amoebae are commonly covered with patches of faecal pellets. Locomotive forms vary in size. Rounded vesicular nucleus 6€”11mm in diameter with single spherical central nucleolus. Floating form of radial type, with a number of fine, tapering hyaline pseudopodia.
Ultrastructure: Cell surface is covered with glycostyles about 100 nm in length; simple, filaments present among them.

 

Dimensions: Locomotive forms 25€”80 µm in greatest dimension (average 42€”52 µm). Nucleus 6€”11 µm in diameter.

 

Ecology: Freshwater, in different water types. Common in moist-chamber-slides where it multiplies easily.

 

Vannella simplex
Vannella simplex
Vannella simplex
Vannella simplex
Vannella simplex
Floating form (left) and locomotive form of the same specimen, with a large load of faecal pellets - Fochteloërveen
Vannella simplex
Vannella simplex
Cells c. 50 µm broad
Vannella simplex
Vannella simplex
Shell 53 µm broad
Vannella simplex
Vannella simplex
Shell 60 µm broad.
Vannella cf lata
Vannella cf lata
Vannella cf lata
Vannella cf lata
Vannella cf lata