Lecythium hyalinum
Lecythium hyalinum

Lecythium hyalinum Hertwig & Lesser, 1874 emend. Dumack et al., 2016.

Diagnosis: Test: round or spherical in shape. Nucleus: ellipsoid or spherical, about 11.5-21 µm in width. Nucleolus:one, rarely two adhering, round, 4-8 µm in diameter; central to nucleus. Aperture: roundish, vacuolated cytoplasm arises from the aperture. Cells show a clear zonation (apical to basal): (I) zone of nucleus (no granules or vacuoles), (II) zone of granules (III) zone of food vacuoles (IV) highly vacuolated cytoplasm in front of the aperture (contractile vacuoles) of which branching and anastomosing filopodia arise. Locomotion: (i) actively creeping, filopodia rarely extend longer than 70 µm; (ii) swimming with extended, non-branched and non-anastomosed and slowly moving filopodia. Filopodia with small granules attached to cytoskeletal filaments occur. Cell division: longitudinal, binary.

Dimensions: literature: 30-45 (Wailes); 18-50 µm (length), 24-61 µm (width), ratio 0.7-1 µm (Dumack et al. 2016; my measurements 27-44 µm.

Ecology: Prey: unicellular algae, no ingestion of bacteria observed. Very common and often abundant in different types of fresh water.

Remarks: This species is probably identical with Chlamydophrys stercorea. I have seen numerous specimens with the same anastomosing and spumose filopodia as described for C. stercorea. Distinction between Chlamydophrys and Lecythium is based on the presence of longitudinal division in Lecythium (Fresenius, Belar, 1921) and budding (Knospen) in Chlamydophrys (Belar, 1921).

Lecythium hyalinum
Lecythium hyalinum, after Belar, 1921
Lecythium hyalinum
Lecythium hyalinum, three cells
Lecythium hyalinum
Three united cells of Lecythium hyalinum. Each cell about 27 µm.
Lecythium hyalinum
Lecythium hyalinum
The pseudostome is flexible; the same specimen within two minutes.
Lecythium hyalinum
Lecythium hyalinum
Lecythium hyalinum
Lecythium hyalinum
Cell with flexible pseudostome and vacuolated cytoplasm
Lecythium hyalinum
Lecythium hyalinum
Lecythium hyalinum with filopodia
Lecythium hyalinum
Lecythium hyalinum
Details of the cell above; notice the typical granules.
Lecythium hyalinum
Lecythium hyalinum, note the large nucleus; when the amoeba is disturbed, it may form a clear globule of plasma around the exterior of its pseudostome.
Lecythium hyalinum
The aperture can be tubular and retracted into the body between folds.
Lecythium hyalinum
A specimen with a very small aperture, only a small tube.
Lecythium hyalinum
Lecythium hyalinum, dividing
Lecythium hyalinum
Lecythium hyalinum, branching and sometimes anastomosing filopodia
Lecythium hyalinum
Lecythium hyalinum
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