Gloeothece tepidariorum
(A.Braun) Lagerheim, 1883
Most likely ID: n.a.
Synonyms: Gloeocapsa tepidariorum, Gloeothece rupestris var. tepidariorum
Sampling location: Pond of the convent Hegne
Phylogenetic tree: Gloeothece tepidariorum
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, 8–15 µm long, 5-6.2 µm wide
- cells colored pale blue-green, grey-green or olive-green
In October 2023, I found only very few colonies of Gloeothece tepidariorum 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 tepidariorum 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.
The cells of the similar species Gloethece membranacea are smaller with a length of 7–8.8 µm and the gelatinous sheath of Gloethece fusco-lutea is colored yellowish to brownish.
Fig. 1 a-b: Gloeothece tepidariorum. 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.