Belonocystis spec. or Luffisphaera??
Diagnosis: I found some cells in a sample from a water inlet for tap water infiltration in the dunes. It was very oligotrophic water. All cells looked like a Belonocystis species, with waving filopodia without granules and with V-shaped spines, like the Eiffel tower. The filopodia are relatively short compared with other Belonocystis species, nearly rod-shaped. One cell was observed with some branched filopodia attached to the cover glass.
Dimensions: cell body 11-12 µm in diameter; spines c. 6.6-7.8 µm long and c. 2.5-2.9 µm broad at the base; nucleus c.3.8 µm; filopodia c. 15-16 µm long (n=5).
Remarks: These cells could be an undescribed Belonocystis species, but SEM research is necessary.