Saccamoeba wellneri Siemensma, 1987
Diagnosis: Locomotive form behavior and form typical of genus, with shallow hyaline cap in locomotion; locomotion slightly sigmoid; nucleus with central globular nucleolus; crystals crescent-shaped, with a thickened central area; uroid often a papillated bulb; contractile vacuole slightly bulging at the posterior end.
Dimensions: 96-130 µm; nucleus 12-21 µm.
Ecology: freshwater, Europe; several water types, both polluted and mesotrophic.
Remarks: The most remarkable feature of this species is the bilaterally symmetric shape of the crystals, resembling a "croissant", a French roll.
The name "wellneri" refers to my friend Rob Wellner, who introduced me into the world of protists.