Genus Netzelia Ogden, 1979
Diagnosis: shell ovoid, circular in cross-section; aperture lobed with a thick organic rim or necklace, made of small idiosomes (homemade siliceous elements). Netzelia differs from Difflugia in its ability to build its test completely from idiosomes with sometimes foreign material (xenosomes) like mineral grains and diatom frustules.
One main shell character which distinguishes Netzelia from Difflugia are the embedded idiosomes which often have a characteristic ‘nail’ shape. The proportion of these elements in the shell matrix is dependent, in part, on the availability of other siliceous material, however, they can construct a complete casing composed of just these elements.The dimensions of the ‘nails’ may vary, although such variation is usually limited to the length of the shaft of the nail, not the diameter of the head (Ogden and Meisterfeld, 1989).