Zivkovicia spectabilis, 200 µm long; the right image is viewed through the aperture
Zivkovicia spectabilis (Penard, 1902)
Diagnosis: test pyriform, circular in oral view, with a clear broad neck; test covered with sand- or quartz-grains arranged on an organic matrix; aperture circular; internally at the junction of the neck with a perforated diaphragm, with two holes.
Dimensions: Penard: length of shell 125-170 µm; my measurements: µm.
Ecology: in sediment of mesotrophic ditches (Naardermeer, the 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 spectabilis, both arrows point to the internal diaphragm.
Zivkovicia spectabilis, with diaphragm; The image is composed of two microphotos 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, from Penard, 1902.
Zivkovicia spectabilis, both arrows point to the bridge in the diaphragm. B shows a look into the aperture.
Zivkovicia spectabilis, 123 µm, Tirol - Austria
Diaphragm, with two holes. The same image but now manipulated so that the two holes are better visible.
Zivkovicia spectabilis, 200 µm long; the right image has been stacked