(Ehrenb.) N.E.Br. Sundström (1986: 44, figs 20, 114, 116–118)
Priddle et al. (1990: 117, pl. 15.1, fig. 6), Kang & Lee (1995: 260, fig. 6D), Hasle & Syvertsen (1997: 149, tab. 33), Armand & Zielinski (2001, pl. 3a, figs 4, 5)
Cells solitary, in pairs or in long chains, long, cylindrical or slightly swollen. Valves acutely conical, bilaterally symmetrical; apical axis 6.5–42 µm. Process long (often broken during the preparation of material for microscopy), tapering. Otaria visible by LM, pointed, extending for several microns along the basal part of the process. Claspers present, visible by LM.
Heard I.; inshore waters of Davis Station, East Antarctica; Southern Ocean, offshore Prydz Bay, 67°01’S 77°43’E; Bransfield Strait (Kang & Lee, 1995); Weddell and Bellingshausen Seas (Hendey, 1937); surface sediments from Weddell Sea and Scotia Sea (Armand & Zielinski, 2001).
Rhizosolenia antennata f. antennata (Fig. 2.36g, h) is thought to represent the resting spore of R. antennata f. semispina (Sundström, 1986; Priddle et al., 1990; Hasle & Syvertsen, 1997). The former has two (paired) processes arising from each valve, the otaria are contiguous and claspers are lacking. Its distribution is generally assumed to include Antarctic coasts, northwards to the edge of the sea-ice zone. Reports from Antarctic waters have appeared under the names R. bidens (Kopczyńska et al., 1986) and R. hebetata f. bidens (Priddle et al., 1990).