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Ocean Ecosystems/ESRIG, University of Groningen and Arctic Centre, University of Groningen and the RaTS program, British Antarctic Survey.

Authority

(Grunow) Jörg. (Jörgensen, 1905: 97, pl. 6, fig. 7)

Class

Diatomophyceae

Order

Centrales

Family

Thalassiosiraceae

Synonyms

Podosira glacialis (Grunow) Cleve (1896: 12, pl. 2, figs 17–20)
Lauderia glacialis (Grunow) Gran (1900: 111, pl. 9, figs 10–14)
Porosira antarctica O.G.Kozlova (1962: 8, pl. 2, fig. 1; pl. 3, fig. 1; 1967: 54, fig. 1)

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Basionym

Podosira hormoides var. glacialis Grunow (1884: 108, pl. E, fig. 32)

Additional References

Manguin (1954: 20), Jousé et al. (1962: 66, pl. 4, fig. 16, as P. antarctica), Priddle & Fryxell (1985: 142, figs A–C), Hasle & Syvertsen (1997: 43, pl. 3, tab. 5)

Description

Cells solitary or attached by mucilage threads from valve surfaces to form loose chains (Fig. f), discoid to cylindrical. Valves circular, 30–40 µm diameter; pervalvar axis 12–64 µm. Areolation radial to irregular, sometimes indistinct; areolae 25–26 in 10 µm, loculate, with external foramina and internal cribra. Strutted processes scattered over valve face (Fig. c, d), 4–6 in 10 µm, simple or with short tubes from which mucilage threads emerge. Labiate process solitary, inside margin (Fig. d). Girdle bands with areolae similar to valves (Fig. e). Chloroplasts small, discoid, numerous.

Distribution

Southern Ocean, south of Australia and near Davis Station, East Antarctica; type locality, Zemlya Frantsa-Iosifa (Franz Josef Land), Arctic Ocean (Grunow, 1884); Heard I. (Manguin, 1954); bipolar distribution (Hasle & Syvertsen, 1997).

Comments

Cells collected near Davis Station were discoid in shape with a pervalvar axis of 12–22 µm.

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