Haplomyxa spec.

Description: The cell had a cylindrical flattened body from which numerous granuloreticulopodia emerged. The common shape was more or less sausage-shaped and elongated, varying between 1.3 and 3.5 mm. The cell body was sometimes Y-shaped or had some holes, but only after migration. The cytoplasm always presented several adjacent opposite conspicuous flows. The granuloreticulopodia emerged from any part of the cell. There were two types: a few large ones that could reach a length of over several millimeters and numerous thin ones that formed a network (reticulum) at both sides of the cell body. All pseudopodia showed bidirectional movement of vacuoles, granules and food particles. The cell migrated after some hours to a new location by transferring the whole cytoplasm through one large vein by unidirectional movement. The whole content of the cell, including organelles and nuclei, slowly flowed out of the initial cell body into the new one. Contractile vacuoles were present in both the cytoplasm and the pseudopodia. Nuclei not observed as the specimen was prepared for sequencing. When stationary, the body was sausage-shaped. It did not move or relocate for many hours.
The cytoplasm contained all kind of food particles, e.g., green algae as Phacus sp., blue algae, testate amoebae as Cryptodifflugia sp.

Dimensions: Cell body 1,300-3,500 µm (n=1). Reticulopodium up to several centimeters in diameter.

Ecology: I found this large naked amoeboid when I was searching a Petri dish with material from a shallow pond in nature reserve Lagieskamp, the Netherlands, July 23 2022. This specimen was sampled from a layer of organic sediment. At home, material was transferred into a Petri dish with a pipette.

Remarks: This species is morphologically similar to H. saranae and might be identical.