Zivkovicia spec., 200 µm long; the right image is viewed through the aperture
Zivkovicia spec.
Diagnosis: Shell pyriform, circular in oral view, with a clear broad neck; shell covered with sand- or quartz-grains embedded in an organic cement; aperture circular; internally at the junction of the neck with a perforated diaphragm, with two holes.
Dimensions: Length 198-210 µm.
Ecology: In sediment of mesotrophic water bodies, Netherlands.
Remarks: It’s difficult to get a clear view of the diaphragm. Most often the diaphragm is obscured by debris in the neck.
Zivkovicia spec., with diaphragm; The image is composed of two photos in Photoshop, each made from a slightly different angle to get a clear view through the aperture. Because of these different angles, the composition has a somewhat oval cross section, which is actually circular. Both holes in the diaphragms have also been highlighted and accentuated in Photoshop.
Zivkovicia spectabilis, 221 µm, with oral view (R)
Zivkovicia spectabilis, both arrows point to the bridge in the diaphragm. B shows a look into the aperture.
Zivkovicia spectabilis, 200 µm long; the right image has been stacked
