Crucigenia mucronata
(G.M. Smith) Komárek, 1974
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Pond of the waste disposal company Constance
Phylogenetic tree: Crucigenia mucronata
Diagnosis:
- coenobia square with square gap in center
- forming composite syncoenobia without gelatinous sheath
- cells irregular oval or trapezoid
- outer side of cell almost straight, inner side convex
- apices slightly tapered with warts
- length 6–9 µm, width 3–6 µm
- chloroplast parietal, one pyrenoid
- planktonic lifestyle
So far, I have found Crucigenia mucronata only once in the plankton of the pond of the waste disposal company Constance. This pond is highly eutrophic. This matches the descriptions by Komarek & Fott (1983), who described it as a rare species in the plankton of eutrophic waters.
In my finding, it was a large, contiguous synzoenobium consisting of about 10–15 coenobia with 8–16 cells. In the coenobia, the cells were arranged in a square pattern. The cells were either flat or slightly convex on the outward-facing side, while the inward-facing side was distinctly convex (s. fig. 2 a-b). The cells had a length of 7.0–8.5 µm. The apices were shaped into short warts, as is typical for this species (s. fig. 2 a-b). The pyrenoid was clearly visible, as was the cell nucleus in the center of the cell.
Fig. 1 a-b: Crucigenia mucronata. D = 90 µm (of syncoenobium). Two focal planes of a syncoenobium of several coenobia of 8-16 cells. Obj. 100 X.
Fig. 2 a-b: Crucigenia mucronata. L = 7.0–8.5 µm (of cells). Two crops of the fig. 1 a-b with the cells in detail. Note the wart-shaped protuberances at the apices of the cells. Nu = nucleus, PY = pyrenoid. Obj. 100 X.