Cucurbitella mespiliformis Penard, 1902
Diagnosis: Shell ovoid, with distinct anterior addition of an apertural collar, dark grey or opaque in color, robust; outline regular, body constructed of small to medium, angular mineral grains. Organic cement seldom seen as surface feature. Diameter of collar just less than half diameter of shell, composed of small mineral grains, 3-5-lobed. Aperture a small circular opening recessed within the collar, on a level with the main body wall. Single large, vesicular nucleus with a large central nucleolus, one or more contractile vacuoles, symbiotic zoochlorellae in cytoplasm; numerous, short, lobose pseudopodia.
Dimensions: Penard 120-140 µm; Cash 116-140 µm; my measurements 110-132 µm long.
Ecology: Freshwater; on waterplants and in debris.
I found this species in ‘t Hol in Kortenhoef, the Bert Bospad in Loosdrecht and Den Treek in Amersfoort. At the latter location, it was abundant. This species has never been recorded by Hoogenraad & De Groot (1940), despite their intensive survey of testate amoebae in the Netherlands.