Keratella serrulata Ehrenberg, 1838
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Suploch (Island Hiddensee)
Phylogenetic tree: Keratella serrulata
Diagnosis:
- body almost rectangular
- length 187–300 µm, width about 100 µm
- lorica distinctly granulated
- ventral side flat
- dorsal side convex with facet-forming ridges
- central facet hexagonal
- six anterior spines with toothed margins
- two short posterior spines
- one eyespot
So far I have only found Keratelle serrulata once in the Suploch on the island Hiddensee. The specimens were very numerous in the samples.
Keratella serrulata looks like Keratella quadrata at small magnifications. However, the posterior spines of Keratella serrulata are strongly reduced or only hinted at, whereas they are long and narrow in Keratella quadrata. In addition, the lorica of Keratella quadrata is smooth without granulation or serrated structures.
The lorica of Keratella serrulata is covered by distinct granules and the anterior spines (especially those on the ventral side) show clearly toothed margins (s. fig. 2 b). The facets on the convex dorsal side are clearly pronounced. The facet in the center is symmetrically hexagonal in shape (s. fig. 2 a).
More images and information on Keratella serrulata: Michael Plewka-Freshwater life-Keratella serrulata
Fig. 1 a-c: Keratella serrulata. L = 220 µm. Three focal planes of a freely swimming specimen from dorsal. Obj. 40 X.
Fig. 2 a-b: Keratella serrulata. L = 225 µm. The slightly squashes specimen from dorsal (a) and from ventral (b). Note the hexagonal central facet (CF) of the dorsal side and the toothed anterior spines (arrow). PS = short posterior spines. Obj. 40 X.