Snowella lacustris
(Chodat) Komárek & Hindák 1988
Most likely ID: n.a.
Synonyms: Gomphosphaeria lacustris, Coelosphaerium lacustre
Sampling location: Mühlweiher Litzelstetten
Phylogenetic tree: Snowella lacustris
Diagnosis:
- colonies spherical or ovoid with mucilaginous envelope
- colonies about 80 µm in diameter
- cells ovoid, length 2–4 µm, width 1.5–3.5 µm
- pale grey-blue or blue-green, without vesicles
- cells in peripherical layer at distal end of branched, mucilaginous stalks
- cells are separated from each other in yound colonies
- stalks originating in center of colony
- planktonic lifestyle
I have only found Snowella lacustris once before in the plankton of the Mühlweiher Litzelstetten. However, the colonies were very sparse in the plankton samples. Snowella lacustris is much rarer in my localities than the similar species Snowella litoralis.
The colonies in my population were all smaller than 30 µm in size (squashed coloines 30–45 µm). Often the spherical colonies were still connected with their gelatinous envelopes, so that I also found agglomerates of 2–6 colonies. The center of the colonies is formed by gelatinous, branched stalks, at the ends of which sit the ovoid cells. The cells are all single-layered in the periphery. They were constantly 4.0–4.2 µm long in my population. The similar species Snowella litoralis has spherical cells. The similar genus Gomphosphaeria has cells more than twice as large (8-12 µm), which remain connected after division and then appear heart-shaped.
Fig. 1 a-b: Snowella lacustris. D = 30–40 µm (of colonies). Two focal planes of four squashed colonies. Note the branche mucilaginous stalk (MS) in the center of the colonies. Obj. 100 X.
Fig. 2: Snowella lacustris. D = 30–45 µm (of colonies). An agglomerate of 6 squashed colonies. Obj. 100 X.
Fig. 3: Snowella lacustris. L = 4.0–4.2 µm (of cells). A crop of fig. 2 with the ovoid cells in details. Obj. 100 X.