world of amoeboid organisms

Choanocystis symna
From Zlatogursky, 2014

Choanocystis symna Zlatogursky, 2014

Diagnosis: Cell body ca. 6.7 µm in diameter. Axopodia three–five times longer than a cell diameter. Plate-scales dumbbell-shaped with a median constriction. Circular lines, parallel to the border of the scale sometimes can be seen. The shafts of spine-scales can be straight, but usually it is slightly curved towards the scale base. Length of plate-scales 4.4–5.0 µm (ca. 4.7 µm); width 1.62–1.90 µm (ca. 1.71 µm). Spine-scales with heart-shaped bases. Sometimes a small circular depression is located on the base at the place of the shaft location. Distal ends of spine-scales bear from three to five (usually four) short teeth. Length of spine-scales 3.9–6.7 µm (ca. 5.1 µm). Cells tightly attach to the bottom of Petri dish or, very rarely, float. No rolling movement was observed.

Ecology: Freshwater. Lake Symniakhovskoe, Valamo island, North-Western Russia, 61°22′912″N, 30°58′503″E.

Remarks: There are only two more described species of Choanocystis with dumbbell-shaped plate-scales and teeth-bearing spine-scales: C. pantopoda and C. aculeata. C. aculeata is a much larger heliozoan (cell diameter 23–60 µm) and has very different spine-scales which are notably tapering and have short protrusions (“nodules”) in proximal part of the shaft. This species also has from five to eleven teeth on the spine-scale tip (Dürrschmidt 1985, Siemensma and Roijackers 1988). C. pantopoda spine-scales are three times longer than plate-scales, while in C. symna only two times longer. The length of scales is 25–30 µm in C. pantopoda, while in C. symna it is only about 5 µm. The number of teeth in C. pantopoda is four to six (Siemensma 1991), but six teeth have never been observed in C. symna. (From Zlatogursky, 2014).

Recent posts

Penardochlamys arcelloides

P. arcelloides – from Penard, 1904 Penardochlamys arcelloides  (Penard, 1904) Deflandre, 1953 Diagnosis: Colorless or very slightly yellowish envelope, bag or cauldron-shaped, very thin, chitinous,

Read More »

Reticulomyxa hannae

R. hannae, plasmodium – photomicrograph Steffen Clauss Reticulomyxa hannae Völcker and Clauß, 2020 Diagnosis: Trophozoites surrounded by a very thin mucous envelope, with slowly moving plasmodia, variable

Read More »

Velamentofex saxonensis

V. saxonensis, feeding (photomicrograph Steffen Clauss) Velamentofex saxonensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 30-95 μm, granuloreticulopodia up to 1000 μm long. with a hyaline, thin

Read More »

Velamentofex tyrolensis

V. tyrolensis (photomicrograph Steffen Clauss) Velamentofex tyrolensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 98-125 μm, with reticulopodia up to 300 μm long, with a hyaline,

Read More »

Velamentofex berolinensis

V. berolinensis Velamentofex berolinensis Völcker and Clauß, 2020 Diagnosis: Trophozoites ovoid, 50-300 µm, with a hyaline, extremely flexible, membranous test. Nuclei numerous, 11.6-16.2 µm in diameter,

Read More »


 Lieberkuehniidae  Siemensma, Holzmann, Apothéloz-Perret-Gentil, Clauß, Voelcker, Bettighofer, Khanipour Roshan, Walden, Dumack and Pawlowski, 2020 Diagnosis: Multinucleate organic-walled monothalamous foraminifera. Test very flexible, elongated to broadly

Read More »