(Manguin) Hasle (1975: 122, figs 114–120)
Rhizosolenia tenuijuncta Manguin (1957: 118, fig. 15; 1960: 270, figs 76, 77)
Priddle & Fryxell (1985: 60, figs A, B), Hasle & Syvertsen (1997: 167, tab. 37)
Cells solitary or in short chains, weakly silicified, cylindrical, straight, slightly curved or undulating; pervalvar axis 18–55 µm. Valves flat, circular to oval; apical axis 6–28 µm, with fine costae radiating from a central labiate process (Fig. b). Girdle composed of half-bands, 5–9 in 10 µm, finely ribbed, with ribs 28–36 in 10 µm; interlocking of the band ends aligned in a straight or weakly spiral arrangement along pervalvar axis (Fig. c). Areolae poroid, rectangular, unoccluded (Fig. b). Chloroplasts small, discoid, numerous. Nucleus usually prominent and central in cell.
Coastal waters near Davis Station, East Antarctica; Drygalski Glacier, Ross Sea; southern cold-water region (Hasle & Syvertsen, 1997); Terre Adélie (Manguin, 1960); Weddell-Scotia Confluence (Garrison et al., 1987).