Observations by davidfbird

Genus is uncertain. Cells randomly placed in a spherical gelatinous colony, without sheaths, uncoloured. Space between cells greater than cell diameter. Cell size 5-6 µm. From a subaerial community growing on an abandoned sock in a flooded limestone quarry. See: https://inaturalist.ca/observations/208411876

Violet-black cells in gelatinous sheaths at the surface of a layer of gelatinous cyanobacteria, growing on a lost sock in the mud of a flooded abandoned limestone quarry. It is Gloeocapsa cordae, I think, the new name for "Gloeocapsa violacea* (link: https://www.algaebase.org/search/species/detail/?species_id=164143). The violet capsule absorbs so much light that it is difficult to induce autofluorescence in the chlorophyll of the cell inside. The first picture shows the violet layer beside some Trentepohlia. The various pictures demonstrate the colours in contrast to some of the other species present (Hassallia, Trentepohlia). Cells themselves are 3-6 µm and the capsules are 6-12 µm. The surface violet-black layer covers a deep layer of gelatinous cells inside lamellated mucilaginous sheaths, of different generations. I think these are also Gloeocapsa cordae, but I'm not sure, because the difference in coloration is usually stark and abrupt (though not alwys - see photos 6 and 7).
Part of a gelatinous community: https://inaturalist.ca/observations/208411876.