Apogromia spec. from brackish water

Diagnosis: Shell is hyaline and colorless, irregularly of shape. The shape of the test is more or less broadly pyriform with a broad aperture without any distinct neck. The test wall is very thin, in some specimens hardly visible light-microscopically. The protoplast is irregular of shape. Through the pseudostome a pseudopodium is extended, which branches outside the aperture into several granulopodia. These pseudopodia also bend and branch. The protoplast does not fill the test completely. The vesicular nucleus is located near the aboral end of the cell. The cytoplasm contains some small granules. No contractile vacuole was present. Each pseudopodium has a number of granules.

Dimensions: Diameter of the test c. 26 µm (n=8), diameter of nucleus about 4 µm.

Ecology: Brackish water (salinity 1.3 %) in a small pond on the island Schiermonnikoog, the Netherlands (2018, ).

Remarks: This Apogromia species is remarkable because it preys on relatively large diatoms. Individuals can contain up to three diatoms. The test is not very distinct.