(Grunow) Medlin, in Medlin & Round (1986: 216, figs 64–70)
Gomphonema kamtschaticum Grunow (1878: 109(12), pl. 3, fig. 4)
Medlin & Round (1990: 157, pl. 20.1, fig. 2)
Cells solitary, clavate, sometimes with a short stalk, often lying in girdle view. Valves linear to lanceolate, with rounded apices; apical axis 18–70 µm; transapical axis 4–11 µm; pervalvar axis at foot pole 2.9–3.1 µm, at head pole 8.5–10.5 µm. Transapical striae slightly radiating throughout, 16–23 in 10 µm (but somewhat fewer on primary valve), uniseriate, containing slit-like poroids. Raphe central, present on both valves; central endings expanded and pore-like; terminal endings hooked at foot pole, but reduced at head pole. Cingulum composed of 4 non-porous bands, the 2 at the foot pole reduced to ligulae.
Near Davis Station, East Antarctica; Renwick Glacier; Prydz Bay.
Specimens collected near Davis Station, often epiphytic on macroalgae or the underside of the sea-ice, agree with the description provided by Medlin (Medlin & Round, 1986). Other possible Antarctic varieties were also mentioned by Medlin (1990), and P. kamtschaticum var. antarctica, intermediate between P. kamtschaticum and P. groenlandicum Østrup was briefly described by Peragallo (1921). Medlin commented: “The varieties of P. kamtschaticum will probably be described as separate species”.