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Vannella arabica CCAP 1589/16.

Olympus CK2, Phase contrast
Locomotive forms, nucleus.

Photo: A.Smirnov

Basic references for identification:

  • Page F.C. (1980) A key to marine species of Vannella (Sarcodina: Gymnamoebia), with description of new species. J. mar. biol. Ass. UK 60: 929-946.
  • Page F.C. (1983) Marine gymnamoebae. Inst. Terr. Ecol., 54 pp
    Vannella arabica Page, 1980 CCAP 1589/16

  • Fan-shaped or semicircular vannella. Frontal hyaloplasm consisted from half and up to 2/3 of the body, usually it formes wide anterior hyaline crescent. In few specimens there are small dorso-lateral ridges or small lobes at the frontal hyaloplasm. Length of the locomotive form on the plastic base of the Petri dish 17-37 mkm (average 27 mkm). Length/Breadth ratio about 0.8.

  • Floating form variable. It may be of radial type, with 3-6 radiating pseudopodia; some pseudopodia may furcate. Sometimes the development may "freeze" and floating amoeba for a long time has short, curved, relatively thick pseudopodia. Similarly to Vannella mira, the floating form may have all cytoplasm in the conical basal thickenings of 2-4 pseudopodia

  • Uninucleate, vesicular nucleus 4.2 - 6.2 mkm in diameter. Single, central, optically homogenous nucleolus about 3 mm in diameter (when measured in live specimens). No crystals in the cytoplasm. No cysts observed.

  • Marine. Observed habitat: Persian gulf region.

  • Identification of a species may be difficult. This amoeba is variable in size and may resemble either small strain of V. ebro or V. mira. Af far as I can outline the difference, it never has that pronounced and numerous ridges on the frontal hyaloplasm, as V. ebro does and is generally smaller than V. ebro. It differs from V. mira in the organisation of the floating from and wider anterior hyaline region. Anotehr similar species, V. anglica can be relatively easily differentiated by the organisation of the floating form and uneven frontal hyaline edge of the cell.

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