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  Morph. Taxon Name Obs.Width Calyptra Granules DkRefr. Necridia Observed Description
1 A Oscillatoria subproboscieda 7.5-10 Yes Yes No Maybe Trichomes between 7.5-10 µm in width (including sheath in this and following taxa). Terminal cell rounded and sometimes swollen with calyptra. Trichomes often found within a sheath. Granules present along transverse walls
2 B Oscillatoria subproboscieda 9-12 Yes Yes No Maybe Trichomes between 9-12 µm in width. Similar to morphotype A but wider and with more numerous granules. These granules may be gas vacuoles, providing protection from the high levels of ultraviolet light encountered in Antarctica
3 C Oscillatoria irrugua 7-9 No Maybe No Maybe Trichomes between 7-9 µm in width and often surrounded by a sheath. Many cells had transverse walls with a convex shape (perhaps separation disks). Terminal cells often attenuated.
4 D Oscillatoria irrugua 7.5-9.5 Yes Maybe Yes Maybe Trichomes between 7.5-9.5 µm in width, sometimes surrounded by a sheath. Dark, refractory surface obscures the cell interior. Cell walls thin. Terminal cell often with a calyptra.
5 E Oscillatoria crouani 8-10 Maybe Yes Yes Maybe Trichomes between 8-10 µm in width. Dark refractory surface obscures cell interior. Granules scattered throughout the trichome. Terminal cells slightly attenuated.
6 F Oscillatoria koettlitzi 7-9.5 Yes Maybe Maybe Yes Trichomes between 7-9.5 µm in width. Terminal cell swollen and often with a calyptra. Cells narrow with a distinct light-dark pattern. Necridia common (1-5) within each trichome.
7 G Oscillatoria koettlitzi 7-9.5 Maybe Yes Maybe Maybe Trichomes between 7-9.5 µm in width. Similar to morphotype E but with much shorter cell length. Terminal cells swollen
8 H Oscillatoria koettlitzi 8-10 No Maybe Yes No Trichomes between 8-10 µm in width. Dense cells with a dark refractory surface and no apparent sheath. Terminal cells often capitate with no visible calyptra. Distinct constrictions at the cell walls. Necridia rare.
9 I Phormidium autumnale 4-6 Yes Yes No No Trichomes between 4-6 µm in width and often with a slight terminal hook. Variable position and quantity of granules. Terminal cell with a calyptra. Could be independent trichomes of Microcoleus vaginatus.
10 J Phormidium autumnale 2.5-3.5 Yes No No No Trichomes between 2.5-3.5 µm in width. Generally, cell walls clearly visible, granules rare. Terminal cell with a calyptra.
11 (no images available) K Phormidium autumnale 2-3.5 Yes No No No Trichomes between 2-3.5 µm in width. Nearly identical to morphotype J except that trichomes arose from common "clump". Trichomes also appeared to taper slightly at the terminal end. Rare occurrence.
12 L Phormidium frigidum <2.5 Maybe Maybe Maybe Maybe Trichomes all less than 2.5 µm in width. Very thin trichomes–probably more than one species. Usually, no cell structures were visible, but occasionally, cells were box-shaped with distinct constrictions at the transverse walls.
13 M Microcoleus vaginatus 4-6 Yes Maybe No No Trichomes between 4-6 µm in width. Nearly identical to morphotype I except that all trichomes were contained within a common sheath. A few trichomes would protrude from the apex of the sheath. Terminal cell with a distinct calyptra. Could be colony of Phormidium autumnale.
14 Chro Gloeocapsa kuetzingiana 2-5 Generally, dark orangeish-brown colony of individual cells, 2-5 µm in diameter. Cells arranged irregularly in a mucilaginous sheath. Colonies range from 7-78 µm in width and contained 3-100+ cells.
15 Nost Nostoc spp. 3-5 Ranged in growth from individual trichomes to dense irregularly shaped colonies. Trichomes yellowish, 3-5 µm wide, 2-3 µm long and closely packed with colonies. Heterocysts present at both endings and within the trichomes; akinetes observed. Thin sheath surrounded the trichomes while a thick yellow mucilaginous sheath surrounded the colonies. Size of colonies ranged from 10 µm in diameter to over 10 cm2. Juvenile colonies with intercalary heterocysts also found. Dificult to identify to species level without cultures.