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Vannella simplex Various isolates. Locomotive forms.
Nikon DiaPhot, Phase contrast.

Vannella simplex CCAP 1589/2. This strain nearly lost its locomotive capacities due to long culturing, cells are normally flotate being placed in liquid medium. Few locomotive forms that are partly abnormal may be found.
Olympus CK2, Phase contrast

Vannella simplex Nivaa isolate (Smirnov et al., 2002). LM and TEM of cysts.

Photo, TEM: A.Smirnov

Basic references for identification:

  • Smirnov AV, Nassonova ES, Holzmann M, Pawlowski J (2002) Morphological, ecological and molecular studies of Vannella simplex Wohlfarth-Bottermann 1960 (Lobosea, Gymnamoebia), with a new diagnosis of this species. Protist 153: 367-377
  • Wohlfarth-Botterman K (1960) Protistenstudien. X. Licht- und electronenmikroskopische Untersuchungen an der amobe Hyalodiscus simplex n. sp. Protoplasma. 52: 58-107
  • Page FC (1976) An Illustrated Key to Freshwater and Soil Amoebae. Freshwater Biol Assoc, Ambleside
  • Page FC (1988) A new key to freshwater and soil gymnamoebae. Freshwater Biol Assoc, Ambleside, UK
    Vannella simplex (Wohlfarth-Bottermann, 1960) Smirnov, Nassonova, Holzmann and Pawlowski, 2002 CCAP 1589/2 (type strain - neotype)

  • The shape of locomotive cells is highly variable. Cells may be crescent-shaped, with a length/breadth ratio less than 0.5 or fan-shaped, with pronounced "tail" and l/b ratio up to 2.0. Locomotive form may reach a maximum dimension of 60 mkm; usual sizes vary from 42 to 50 mkm in length and breadth.

  • The floating form is of radial type, non - symmetrical, with one to nine pointed, tapering hyaline pseudopodia without basal thickening.

  • Vesicular nucleus is 6 - 11 mkm in diameter with one central or slightly eccentric nucleolus. Normally mononucleate, but some strains tend to have one or two supernumerary nuclei (Page, 1988).

  • Some cultured strains are always covered with faecal pellets, whereas others may lose this tendency during cultivation. Contractile vacuoles always exist in freshwater strains, but were not found in brackish-water cultures of the V. simplex Niva isolate (Smirnov et al., 2002).

  • Simple filaments among the glycostyles of the cell coat may be absent or indistinguishable in some strains.

  • Cyst formation was observed in the V. simplex Niva strain under brackish water conditions, but not in freshwater cultures. Cysts are rounded, single-walled, with a diameter of 16-26 mkm. The cell surface inside the cyst is characteristically wrinkled. The thickness of the cyst wall is 1.1-1.8 mkm.

  • Habitat: freshwater, brackish-water. Known from numerous locations in Europe, probably from Asia and North America

  • Vannella simplex perhaps is among few relatively easily recognisable amoebae species. However, one should not forget about the existence of "Vannella cirifera" Frenzel, 1874 (see Page, 1976 for photos of this "species"). Despite the low-detailed description of this species, it may mean that there are V. simplex - like species not describet yet.

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