Gloeothece membranacea
(Rabenhorst) Bornet, 1892
Most likely ID: n.a.
Synonyms: Aphanocapsa membranacea, Aphanothece membranacea
Sampling location: Pond of the convent Hegne
Phylogenetic tree: Gloeothece membranacea
Diagnosis:
- colony spherical, irregular or rectangular
- colony surrounded by common mucilage, colorless or slightly pink
- cells surrounded by sharply defined mucus envelopes, concentrically layered
- cells ellipsoid or elongated oval, 7.5–9.9 µm long 4.5–5.2 µm broad
- cells colored blue-green or olive-green
In October 2023, I found only very few colonies of Gloeothece membranacea in the mud of the pond of the convent Hegne. The colonies are easily recognizable even at low magnifications due to the highly refractive gelatinous sheath. The cells of Gloeothece membranacea are quite large for a cyanobacteria at around 10 µm in length. Another striking feature is the sharply defined mucus envelope of the individual cells in the colony. This can also be multi-layered. In my population, the cells had a rather pale olive-green color.
Fig. 1 a-b: Gloeothece membranacea. L = 10.4–11.2 µm (of cells). Two focal planes of an almost spherical colony. Note the sharply defined mucus envelopes of the cells. Obj. 100 X.