A.W.F.Schmidt (Østrup) Heiden (1905), in Schmidt et al. (1874–1959: tab. 260, figs 3–8)
Navicula pinnularia var. constricta Østrup (1895: 419, pl. 4, figs 23, 24)
Heiden & Kolbe (1928: 596), Poulin (1990: 140, pl. 18.1, fig. 34)
Cells solitary. Valves lanceolate, but constricted at the centre; valve faces flat; apical axis 35–96 µm; transapical axis 11–19 µm; pervalvar axis c. 4–14 µm. Transapical striae coarse, 10–11 in 10 µm, biseriate (occasionaly triseriate). Raphe endings at valve poles distinctly hooked, deflected in the same direction; central raphe endings expanded. Chloroplasts 2, plate-like.
Sea-ice near Davis Station, East Antarctica; Arctic to Antarctic (Poulin, 1990); in pack-ice, “Gaussberg”, Davis Sea (Heiden & Kolbe, 1928); coastal waters off Syowa Station, East Antarctica (Ishikawa et al., 2001).
A single cell of P. quadratarea var. soederlundii Cleve was also collected in sea-ice near Davis Station. This variety is smaller than var. constricta, being 35–66 µm long and with 11–13 striae in 10 µm. Var. soederlundii (Fig. 2.90d) was previously recorded off Heard I. and the Davis Sea, East Antarctica by Heiden & Kolbe (1928: 595, tab. 2, figs 31, 32).