Difflugia umbilicata Penard, 1902
= Difflugia pyriformis var. umbilicata Penard, 1902
Diagnosis: Shell elongated ovoid; fundus usually crowned by a bud-shaped ornament; shell composed of quartz particles, sometimes mixed with fragments of diatom shells; pseudostome circular.
Dimensions: Penard: length 200-275 µm; my measurements 179-245 µm.
Ecology: I found this species occasionally in sediment of a ditch in the nature reserve Naardermeer, the Netherlands.