Vannella danica Smirnov Nassonova, Chao and Cavalier-Smith, 2007
Diagnosis: Locomotive form semicircular or fan-shaped. Single vesicular nucleus, with central or slightly eccentric rounded nucleolus. Cultured cells always densely covered with rounded faecal pellets. Cysts rounded, always surrounded with a layer of fecal pellets. Single cyst wall, 1.1-1.8 µm in thickness, consists of a filamentous material.
Ultrastructure: Cell surface consists of glycostyles about 115 nm in length, without simple filaments among them.
Dimensions: Length of the locomotive form 25-50 µm (average 32 µm); breadth 25-50 µm (average 39 µm). Length/breadth ratio 0.5-1.25 (average 0.82).
Ecology: brackish-water (Baltic Sea)
Remarks: trophozoites resemble V. simplex, but are somewhat smaller. Cyst-forming, in contrast with the known strains of V. simplex. No simple filaments among glycostyles.