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Mastigamoeba setosa, n=nucleus

Mastigamoeba setosa Goldschmidt, 1907

Diagnosis: cell broad elliptical with thick membrane, densely covered with a network-like tectum embedded with spines of different length; cytoplasm with some small empty vacuoles and food vacuoles; cilium about 1½ – 3 times body length; no pseudopodia, sometimes a single, temporary lateral bulge of hyaloplasm; nucleus with some peripheral nucleolar fragments, sometimes with lacunae; cilium connected to the nucleus.

Dimensions: Goldschmidt up to 140 µm, Hoogenraad and de Groot (1940): about 100 µm; my measurements about 50-70 µm (n=5), nucleus c. 8 µm, spines 3-11 µm.

Ecology: Sediments of ditches. I found my specimens along the Bert Bospad and in the Laegieskamp, the Netherlands.

Remarks: I found two specimens in floating mats of blue algae in February 2013, shortly after the ice on the ditch had melted. The spines seems loosely distributed over the cell membrane. Some spines were detached and were freely between the other spines. Two other specimens also came up in a sample from floating bottom sediments.

Photomicrographs with a SEM of an air-dried specimens revealed the existence of a network-like covering and hollow spines with to sharp teeth on top. In LM this network is visible as a layer of granules.

Mastigamoeba setosa, air-dried – SEM image Eckhard Voelcker
Mastigamoeba setosa, air-dried – SEM image Eckhard Voelcker
Mastigamoeba setosa; note where the flagellum passes through the cell membrane (yellow arrow).
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