Vannella arabica CCAP 1589/16.
Olympus CK2, Phase contrast
Locomotive forms, nucleus.
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
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
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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