Cleve (1873: 8, pl. 1, fig. 7)
Lauderia borealis Gran (1900: 109, pl. 9, figs 1–8)
Hasle & Syvertsen (1996: 36, pl. 1), Round et al. (1990: 150)
Cells in chains attached by threads from strutted processes on valve faces, discoid. Valves circular, 24–75 µm diameter. Areolation appearing as barely discernible ribs radiating from a central annulus; ribs more than 30 in 10 µm, anastomosing near the margin. Strutted processes scattered over valve surface and in a conspicuous marginal ring; processes 10 in 10 µm, with well-developed external tubes. Labiate process solitary, just inside marginal ring of strutted processes. Plastids small, discoid.
Coastal waters off Davis Station, East Antarctica.
Superficially this species resembles members of the genus Porosira, but it has distinctive external extensions to the strutted processes.