Hedriocystis pellucida
Hertwig & Lesser, 1874
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Ulmisried, Simmelried
Phylogenetic tree: Hedriocystis pellucida
Diagnosis:
- cell in a polygonal shell with long stalk
- shell with pores on conical elevations
- pseudopodia arise from pores
- pseudopodia granulated
- diameter of cell 10-12 µm
- diameter of shell 16-30 µm
- length of stalk 36-90 µm
- spherical nucleus with central nucleolus
- one or several contractile vacuoles
I find Hedriocystis pellucida in Ulmisried and Simmelried. The specimens are difficult to find in fresh samples. However, Hedriocystis pellucida likes to settle on the floating coverslip and is then easy to observe.
Hedriocystis pellucida forms a polygonal shell on a long stalk of organic, transparent material (s. figs. 1 a-b and 2). The shell has hump-like elevations with pores. The cell stretches its granulated pseudopodia outwards through these pores to catch prey. Bacteria are almost exclusively used as prey. This is the reason why Hedriocystis pellucida only settles on the floating coverslip when a sufficient growth of bacteria has formed there.
Cyst formation also takes place in the shell, which remains in the shell (s. fig. 4 a-b). The cysts have a diameter of 8–9 µm and are densely covered with short spines.
More images and information on Hedriocystis pellucida: Ferry Siemensma-Microworld-Hedriocystis pellucida
Fig. 1 a-b: Hedriocystis pellucida. L = 58 µm. Two focal planes of a specimen attached to a detritus flake. Nu = nucleus, CV = contractile vacuole. Obj. 60 X.
Fig. 2: Hedriocystis pellucida. L = 64 µm. A specimen with fully extended pseudopodia attached to a floating coverslip. Obj. 100 X.
Fig. 3 a-c: Hedriocystis pellucida. L = 68 µm. Different focal planes of two cells in a shell after cell division. Obj. 100 X.
Fig. 4 a-b: Hedriocystis pellucida. A cyst with a diameter of 8.2 µm. The surface of the cyst is covered with short spines. Obj. 100 X.